encore.cljc

(ns taoensso.encore
  "Extended core library for Clojure/Script that emphasizes:
    * Cross platform API compatibility
    * Flexibility
    * Performance
    * Backwards compatibility

  This lib's mostly for my own use and for advanced users that feel
  comfortable reading this source. Not providing much beginner-oriented
  documentation for this, sorry.

  Quick Taoensso naming conventions:
    **foo** - Dynamic var.
    foo!    - Fn with side effects, or that should otherwise be used cautiously.
    foo?    - Truthy val or fn that returns truthy val.
    foo!?   - Fn that has side effects (or requires caution) and that returns
              a truthy val. Note: !?, not ?!.
    foo$    - Fn that's notably expensive to compute (e.g. hits db).
    foo_    - Dereffable val (e.g. atom, volatile, delay, etc.).
    _       - Unnamed val.
    _foo    - Named but unused val.
    ?foo    - Optional val (emphasize that val may be nil).
    foo*    - A variation of `foo` (e.g. `foo*` macro vs `foo` fn).
    -foo    - Public implementation detail or intermediate (e.g. uncoerced) val.
    >foo    - Val \"to foo\" (e.g. >sender, >host), or fn to put/coerce/transform.
    <foo    - Val \"from foo\" (e.g. <sender, <host), or fn to take/coerce/transform.
    ->foo   - Fn to put/coerce/transform."

  {:author "Peter Taoussanis (@ptaoussanis)"}

  (:refer-clojure :exclude
   [if-let if-some if-not when when-not when-some when-let cond defonce
    run! some? ident? float? boolean? uri? indexed? bytes?
    int? pos-int? neg-int? nat-int?
    simple-ident?   qualified-ident?
    simple-symbol?  qualified-symbol?
    simple-keyword? qualified-keyword?
    format update-in merge merge-with
    memoize])

  #?(:clj
     (:require
      [clojure.string  :as str]
      [clojure.set     :as set]
      [clojure.java.io :as io]
      [clojure.walk    :as walk :refer [macroexpand-all]]
      ;; [clojure.core.async    :as async]
      [clojure.tools.reader.edn :as edn]
      [taoensso.truss :as truss])

     :cljs
     (:require
      [clojure.string      :as str]
      [clojure.set         :as set]
      ;; [cljs.core.async  :as async]
      [cljs.reader]
      [cljs.tools.reader.edn :as edn]
      ;;[goog.crypt.base64 :as base64]
      [goog.object         :as gobj]
      [goog.array          :as garray]
      [goog.string         :as gstr]
      [goog.string.format]
      [goog.string.StringBuffer]
      [goog.events         :as gevents]
      [goog.net.XhrIo      :as gxhr]
      [goog.net.XhrIoPool  :as gxhr-pool]
      [goog.Uri.QueryData  :as gquery-data]
      [goog.net.EventType]
      [goog.net.ErrorCode]
      [taoensso.truss :as truss]))

  #?(:clj
     (:import
      [java.util Date Locale TimeZone]
      [java.text SimpleDateFormat]
      [java.util.concurrent CountDownLatch]
      ;; [org.apache.commons.codec.binary Base64]
      )

     :cljs
     (:require-macros
      [taoensso.encore :as enc-macros :refer
       [have have! have? compile-if
        if-let if-some if-not when when-not when-some when-let -cond cond defonce
        cond! catching -if-cas! now-dt* now-udt* now-nano* min* max* -gc-now?
        name-with-attrs deprecated new-object defalias]])))

(def encore-version [3 13 0])

(comment "∴ ∵ ℕ ℤ ℝ ∞ ≠ ∈ ∉ ⇒⇔ → × ⊃⊂ ⊇⊆ ≡ ¬ ∀ ∃ ∝"
  (set! *unchecked-math* :warn-on-boxed)
  (set! *unchecked-math* false))

(do ; Bootstrap Truss aliases
  (defmacro have  [& args] `(taoensso.truss/have  ~@args))
  (defmacro have? [& args] `(taoensso.truss/have? ~@args)))

;;;; Core macros

#?(:clj
   (defmacro compile-if
     "Evaluates `test`. If it returns logical true (and doesn't throw), expands
     to `then`, otherwise expands to `else`."
     {:style/indent 1}
     ([test then     ] `(compile-if ~test ~then nil)) ; Back compatibility
     ([test then else]
      (if (try (eval test) (catch Throwable _ false))
        `(do ~then)
        `(do ~else)))))

#?(:clj (defmacro compile-when {:style/indent 1} [test & body] `(compile-if ~test (do ~@body) nil)))
#?(:clj
   (compile-if
     ;; Avoiding for edge case where user cares about startup time and has
     ;; `core.async` as dependency but it never gets required anywhere else
     ;; (do (require 'clojure.core.async) true)
     (do (or
           (io/resource "clojure/core/async.clj")
           (io/resource "clojure/core/async.cljc")))
     (def have-core-async? true)
     (def have-core-async? false)))

(comment (require '[clojure.core.async] :verbose))

;;; (:ns &env) is nnil iff compiling for ClojureScript, giving us a way to
;;; write macros that produce different Clj/Cljs code (not something that
;;; .cljx or .cljc currently provide support for):
(defmacro if-clj  [then & [else]] (if (:ns &env) else then))
(defmacro if-cljs [then & [else]] (if (:ns &env) then else))

(defmacro if-let
  "Like `core/if-let` but can bind multiple values for `then` iff all tests
  are truthy, supports internal unconditional `:let`s."
  {:style/indent 1}
  ([bindings then     ] `(if-let ~bindings ~then nil))
  ([bindings then else]
   (let [s (seq bindings)]
     (if s ; (if-let [] true false) => true
       (let [[b1 b2 & bnext] s]
         (if (= b1 :let)
           `(let      ~b2  (if-let ~(vec bnext) ~then ~else))
           `(let [b2# ~b2]
              (if b2#
                (let [~b1 b2#]
                  (if-let ~(vec bnext) ~then ~else))
                ~else))))
       then))))

(defmacro if-some
  "Like `core/if-some` but can bind multiple values for `then` iff all tests
  are non-nil, supports internal unconditional `:let`s."
  {:style/indent 1}
  ([bindings then] `(if-some ~bindings ~then nil))
  ([bindings then else]
   (let [s (seq bindings)]
     (if s ; (if-some [] true false) => true
       (let [[b1 b2 & bnext] s]
         (if (= b1 :let)
           `(let      ~b2  (if-some ~(vec bnext) ~then ~else))
           `(let [b2# ~b2]
              (if (nil? b2#)
                ~else
                (let [~b1 b2#]
                  (if-some ~(vec bnext) ~then ~else))))))
       then))))

(defmacro if-not
  "Like `core/if-not` but acts like `if-let` when given a binding vector
  as test expr."
  ;; Also avoids unnecessary `(not test)`
  {:style/indent 1}
  ([test-or-bindings then]
   (if (vector? test-or-bindings)
     `(if-let ~test-or-bindings nil ~then)
     `(if     ~test-or-bindings nil ~then)))

  ([test-or-bindings then else]
   (if (vector? test-or-bindings)
     `(if-let ~test-or-bindings ~else ~then)
     `(if     ~test-or-bindings ~else ~then))))

(defmacro when
  "Like `core/when` but acts like `when-let` when given a binding vector
  as test expr."
  {:style/indent 1}
  [test-or-bindings & body]
  (if (vector? test-or-bindings)
    `(if-let ~test-or-bindings (do ~@body) nil)
    `(if     ~test-or-bindings (do ~@body) nil)))

(defmacro when-not
  "Like `core/when-not` but acts like `when-let` when given a binding vector
  as test expr."
  {:style/indent 1}
  [test-or-bindings & body]
  (if (vector? test-or-bindings)
    `(if-let ~test-or-bindings nil (do ~@body))
    `(if     ~test-or-bindings nil (do ~@body))))

(defmacro when-some
  {:style/indent 1}
  [test-or-bindings & body]
  (if (vector? test-or-bindings)
    `(if-some       ~test-or-bindings  (do ~@body) nil)
    `(if      (nil? ~test-or-bindings) nil (do ~@body))))

(defmacro when-let
  "Like `core/when-let` but can bind multiple values for `body` iff all tests
  are truthy, supports internal unconditional `:let`s."
  {:style/indent 1}
  ;; Now a feature subset of all-case `when`
  [bindings & body] `(if-let ~bindings (do ~@body)))

(comment
  (if-let   [a :a b (= a :a)] [a b] "else")
  (if-let   [a :a b (= a :b)] [a b] "else")
  (if-some  [a :a b (= a :b)] [a b] "else")
  (when-let [a :a b nil] "true")
  (when-let [:let [a :a b :b] c (str a b)] c))

(defmacro -cond [throw? & clauses]
  (if-let [[test expr & more] (seq clauses)]
    (if-not (next clauses)
      test ; Implicit else
      (case test
        (true :else :default)       expr                             ; Faster than (if <truthy> ...)
        (false nil)                         `(-cond ~throw? ~@more)  ; Faster than (if <falsey> ...)
        :do          `(do          ~expr     (-cond ~throw? ~@more))
        :let         `(let         ~expr     (-cond ~throw? ~@more))

        :return-when `(if-let  [x# ~expr] x# (-cond ~throw? ~@more)) ; Undocumented
        :return-some `(if-some [x# ~expr] x# (-cond ~throw? ~@more)) ; Undocumented
        :when        `(when        ~expr     (-cond ~throw? ~@more)) ; Undocumented
        :when-not    `(when-not    ~expr     (-cond ~throw? ~@more)) ; Undocumented
        :when-some   `(when-some   ~expr     (-cond ~throw? ~@more)) ; Undocumented

        ;;; 3-clause cases
        (:if-let :if-some :if-not)
        (if (empty? more) ; Missing 3rd clause
          (throw
            (ex-info (str "`encore/cond`: missing `then` clause for special test keyword: " test)
              {:test-form test :expr-form expr}))

          (case test
            :if-let  `(if-let  ~expr ~(first more) (-cond ~throw? ~@(next more)))
            :if-some `(if-some ~expr ~(first more) (-cond ~throw? ~@(next more)))
            :if-not  `(if-not  ~expr ~(first more) (-cond ~throw? ~@(next more))) ; Undocumented
            ))

        (if (keyword? test)
          (throw ; Undocumented, but throws at compile-time so easy to catch
            (ex-info (str "`encore/cond`: unrecognized special test keyword: " test)
              {:test-form test :expr-form expr}))

          (if (vector? test) ; Undocumented
            `(if-let ~test ~expr (-cond ~throw? ~@more))

            ;; Experimental, assumes `not` = `core/not`:
            (if (and (list? test) (= (first test) 'not))
              `(if ~(second test) (-cond ~throw? ~@more) ~expr)
              `(if ~test ~expr    (-cond ~throw? ~@more)))))))

    (when throw?
      `(throw (ex-info "`encore/cond!`: no matching clause" {})))))

(defmacro cond
  "Like `core/cond` but supports implicit final `else` clause, and special
  clause keywords for advanced behaviour:

  (cond
    :let [x \"x\"] ; Establish bindings visible to following forms

    :do (println (str \"x value: \" x)) ; Eval expr for side effects

    :if-let [y \"y\"
             z nil]
    \"y and z were both truthy\"

    :if-some [y \"y\"
              z nil]
    \"y and z were both non-nil\")

  :let support inspired by https://github.com/Engelberg/better-cond.
  Simple, flexible way to eliminate deeply-nested control flow code."

  ;; Also avoids unnecessary `(if :else ...)`, etc.
  [& clauses] `(-cond false ~@clauses))

(defmacro cond!
  "Like `cond` but throws on non-match like `case` and `condp`."
  [& clauses] `(-cond true ~@clauses))

(comment
  [(macroexpand-all '(clojure.core/cond nil "a" nil "b" :else "c"))
   (macroexpand-all '(cond nil "a" nil "b" :else "c"))
   (macroexpand-all '(cond nil "a" nil "b" (println "bar")))
   (macroexpand-all '(cond :when true :let [x "x"] :else x))
   (macroexpand-all '(cond false 0 (not false) 1 2))
   (macroexpand-all '(cond [a :A] a))]

  (cond
    :if-not [n "Stu"] "Don't have a name"
    :else             (str n " Smith"))

  (cond  false "false")
  (cond! false "false")

  (cond  :if-let [])
  (cond  :if-let [a :a])
  (cond  :when   [a :a])
  (cond! :return-when (when true  "foo"))
  (cond! :return-when (when false "foo"))

  [(macroexpand-all '(cond  (= 1 0) "a"))
   (macroexpand-all '(cond! (= 1 0) "a"))

   (macroexpand-all '(cond  :let [a :a] (= 1 0) "a"))
   (macroexpand-all '(cond! :let [a :a] (= 1 0) "a"))

   (macroexpand-all '(cond  :if-let [a nil] a (= 1 0) "1=0" #_"default"))
   (macroexpand-all '(cond! :if-let [a nil] a (= 1 0) "1=0" #_"default"))

   (cond  :if-let [a nil] a (= 1 0) "1=0" #_"default")
   (cond! :if-let [a nil] a (= 1 0) "1=0" #_"default")])

(defn name-with-attrs
  "Given a symbol and args, returns [<name-with-attrs-meta> <args>] with
  support for `defn` style `?docstring` and `?attrs-map`."
  ([sym args            ] (name-with-attrs sym args nil))
  ([sym args attrs-merge]
   (let [[?docstring args] (if (and (string? (first args)) (next args)) [(first args) (next args)] [nil args])
         [attrs      args] (if (and (map?    (first args)) (next args)) [(first args) (next args)] [{}  args])
         attrs (if ?docstring (assoc attrs :doc ?docstring) attrs)
         attrs (if (meta sym) (conj (meta sym) attrs) attrs)
         attrs (conj attrs attrs-merge)]
     [(with-meta sym attrs) args])))

(defmacro defonce
  "Like `core/defonce` but supports optional docstring and attrs map."
  {:style/indent 1}
  [sym & args]
  (let [[sym body] (name-with-attrs sym args)]
    `(if-cljs
          (cljs.core/defonce ~sym ~@body)
       (clojure.core/defonce ~sym ~@body))))

#?(:clj
   (defn compiling-cljs?
     "Return truthy iff currently generating Cljs code."
     []
     (when-let [n (find-ns 'cljs.analyzer)]
       (when-let [v (ns-resolve n '*cljs-file*)]
         @v))))

(comment (compiling-cljs?))

;;;; Core fns we'll redefine but need in this ns

(def -core-merge     #?(:clj clojure.core/merge     :cljs cljs.core/merge))
(def -core-update-in #?(:clj clojure.core/update-in :cljs cljs.core/update-in))
(declare merge update-in)

;;;; Secondary macros

#?(:clj
   (defmacro case-eval
     "Like `case` but evals test constants for their compile-time value."
     {:style/indent 1}
     [expr & clauses]
     (let [default (when (odd? (count clauses)) (last clauses))
           clauses (if default (butlast clauses) clauses)]
       `(case ~expr
          ~@(map-indexed (fn [i# form#] (if (even? i#) (eval form#) form#)) clauses)
          ~(when default default)))))

(do
  (defmacro do-nil   [& body] `(do ~@body nil))
  (defmacro do-false [& body] `(do ~@body false))
  (defmacro do-true  [& body] `(do ~@body true)))

(defmacro doto-cond
  "Cross between `doto`, `cond->` and `as->`."
  {:style/indent 1}
  [[sym x] & clauses]
  (assert (even? (count clauses)))
  (let [g (gensym)
        pstep (fn [[test-expr step]]
                `(when-let [~sym ~test-expr] (-> ~g ~step)))]
    `(let [~g ~x]
       ~@(map pstep (partition 2 clauses))
       ~g)))

(defmacro declare-remote
  "Declares given ns-qualified symbols, preserving metadata. Useful for
  circular dependencies."
  [& syms]
  (let [original-ns (str *ns*)]
    `(do ~@(map (fn [s]
                  (let [ns (namespace s)
                        v  (name      s)
                        m  (meta      s)]
                    `(do (in-ns  '~(symbol ns))
                         (declare ~(with-meta (symbol v) m))))) syms)
         (in-ns '~(symbol original-ns)))))

(defmacro defalias
  "Defines an alias for qualified source symbol, preserving its metadata (clj only):
    (defalias my-map-alias clojure.core/map)

  Cannot alias Cljs macros.
  Changes to source are not automatically applied to alias."
  ;; TODO Any way to reliably preserve cljs metadata? See #53, commit 2a63a29, etc.

  ([    src      ] `(defalias ~(symbol (name src)) ~src nil))
  ([sym src      ] `(defalias ~sym                 ~src nil))
  ([sym src attrs]
   (let [attrs (if (string? attrs) {:doc attrs} attrs)] ; Back compatibility
     `(let [attrs# (conj (select-keys (meta (var ~src)) [:doc :arglists :private :macro]) ~attrs)]
        (alter-meta! (def ~sym @(var ~src)) conj attrs#)
        (var ~sym)))))

(comment
  (defalias foo map)
  (defalias taoensso.truss/have)
  (meta #'foo)
  (meta #'have))

;;;; Truss aliases (for back compatibility, convenience)

#?(:clj
   (do
     (defalias taoensso.truss/have)
     (defalias taoensso.truss/have!)
     (defalias taoensso.truss/have?)
     (defalias taoensso.truss/have!?)
     (defalias taoensso.truss/get-dynamic-assertion-data)
     (defalias taoensso.truss/with-dynamic-assertion-data)))

;;;; Edn

(declare map-keys kw-identical?)

(defn read-edn
  "Attempts to pave over differences in:
    `clojure.edn/read-string`, `clojure.tools.edn/read-string`,
    `cljs.reader/read-string`, `cljs.tools.reader/read-string`.
   `cljs.reader` in particular can be a pain."

  ([     s] (read-edn nil s))
  ([opts s]
   ;; First normalize behaviour for unexpected inputs:
   (if (or (nil? s) (identical? s ""))
     nil
     (if-not (string? s)
       (throw (ex-info "`read-edn` attempt against non-nil, non-string arg"
                {:given s :type (type s)}))

       (let [readers (get opts :readers ::dynamic)
             default (get opts :default ::dynamic)

             ;; Nb we ignore as implementation[1] detail:
             ;;  *.tools.reader/*data-readers*,
             ;;  *.tools.reader/default-data-reader-fn*
             ;;
             ;; [1] Lib consumer doesn't care that we've standardized to
             ;;     using tools.reader under the covers

             readers
             (if-not (kw-identical? readers ::dynamic)
               readers
               #?(:clj  clojure.core/*data-readers*

                  ;; Unfortunate (slow), but faster than gc'd memoization in most cases:
                  :cljs (map-keys symbol @cljs.reader/*tag-table*)))

             default
             (if-not (kw-identical? default ::dynamic)
               default
               #?(:clj  clojure.core/*default-data-reader-fn*
                  :cljs @cljs.reader/*default-data-reader-fn*))

             opts (assoc opts :readers readers :default default)]

         #?(:clj  (clojure.tools.reader.edn/read-string opts s)
            :cljs    (cljs.tools.reader.edn/read-string opts s)))))))

(defn pr-edn
  "Prints arg to an edn string readable with `read-edn`."
  ([      x] (pr-edn nil x))
  ([_opts x]
   #?(:cljs (binding [*print-level* nil, *print-length* nil] (pr-str x))
      :clj
      (let [sw (java.io.StringWriter.)]
        (binding [*print-level* nil, *print-length* nil,
                  ;; *out* sw, *print-dup* false
                  ]
          ;; (pr x)
          (print-method x sw) ; Bypass *out*, *print-dup*
          (.toString sw)))
      )))

;;;; Errors

(defn error-data
  "Returns data map iff `x` is an error of any type on platform."
  ;; Note that Clojure 1.7+ now also has `Throwable->map`
  [x]
  (when-let [data-map
             (or (ex-data x) ; ExceptionInfo
                 (when (instance? #?(:clj Throwable :cljs :default) x) {}))]
    (conj
      #?(:clj
         (let [^Throwable t x] ; (catch Throwable t <...>)
           {:err-type   (type                 t)
            :err-msg    (.getLocalizedMessage t)
            :err-cause  (.getCause            t)})

         :cljs
         (let [err x] ; (catch :default t <...)
           {:err-type  (type      err)
            :err-msg   (.-message err)
            :err-cause (.-cause   err)}))

      data-map)))

(comment
  (error-data (Throwable. "foo"))
  (error-data (Exception. "foo"))
  (error-data (ex-info    "foo" {:bar :baz})))

(defmacro catching "Cross-platform try/catch/finally."
  ;; We badly need something like http://dev.clojure.org/jira/browse/CLJ-1293
  ([try-expr                     ] `(catching ~try-expr ~'_ nil))
  ([try-expr error-sym catch-expr]
   `(if-cljs
      (try ~try-expr (catch :default  ~error-sym ~catch-expr))
      (try ~try-expr (catch Throwable ~error-sym ~catch-expr))))
  ([try-expr error-sym catch-expr finally-expr]
   `(if-cljs
      (try ~try-expr (catch :default  ~error-sym ~catch-expr) (finally ~finally-expr))
      (try ~try-expr (catch Throwable ~error-sym ~catch-expr) (finally ~finally-expr)))))

(comment
  (macroexpand '(catching (do "foo") e e (println "finally")))
  (catching (zero? "9")))

(defmacro caught-error-data "Handy for error-throwing unit tests."
  [& body] `(catching (do ~@body nil) e# (error-data e#)))

(comment (caught-error-data (/ 5 0)))

;;;; Type preds, etc.
;; - TODO Could really do with a portable ^boolean hint
;; - Some of these have slowly been getting added to Clojure core; make sure
;;   to :exclude any official preds using the same name

#?(:clj
   (do
     (defn some?
       {:inline (fn [x] `(if (identical? ~x nil) false true))}
       [x] (if (identical? x nil) false true))

     (defn stringy?    [x] (or (keyword? x) (string? x)))
     (defn ident?      [x] (or (keyword? x) (symbol? x)))
     (defn boolean?    [x] (instance? Boolean                           x))
     (defn uri?        [x] (instance? java.net.URI                      x))
     (defn indexed?    [x] (instance? clojure.lang.Indexed              x))
     (defn named?      [x] (instance? clojure.lang.Named                x))
     (defn editable?   [x] (instance? clojure.lang.IEditableCollection  x))
     (defn derefable?  [x] (instance? clojure.lang.IDeref               x))
     (defn throwable?  [x] (instance? Throwable                         x))
     (defn exception?  [x] (instance? Exception                         x))
     (defn error?      [x] (instance? Throwable                         x))
     (defn atom?       [x] (instance? clojure.lang.Atom                 x))
     (defn transient?  [x] (instance? clojure.lang.ITransientCollection x))
     (defn lazy-seq?   [x] (instance? clojure.lang.LazySeq              x))
     (defn re-pattern? [x] (instance? java.util.regex.Pattern           x))

     (defn simple-ident?      [x] (and (ident?   x) (nil? (namespace x))))
     (defn qualified-ident?   [x] (and (ident?   x)       (namespace x) true))
     (defn simple-symbol?     [x] (and (symbol?  x) (nil? (namespace x))))
     (defn qualified-symbol?  [x] (and (symbol?  x)       (namespace x) true))
     (defn simple-keyword?    [x] (and (keyword? x) (nil? (namespace x))))
     (defn qualified-keyword? [x] (and (keyword? x)       (namespace x) true))

     (defn nempty-str? [x] (and (string? x) (not (.isEmpty ^String x))))
     (defn nblank-str? [x] (and (string? x) (not (str/blank? x))))
     (defn nblank?     [x]                  (not (str/blank? x)))
     (defn vec2?       [x] (and (vector? x) (= (count x) 2)))
     (defn vec3?       [x] (and (vector? x) (= (count x) 3))))

   :cljs
   (do
     (defn ^boolean some?       [x] (if (nil? x) false true))
     (defn ^boolean stringy?    [x] (or (keyword? x) (string? x)))
     (defn ^boolean ident?      [x] (or (keyword? x) (symbol? x)))
     (defn ^boolean boolean?    [x] (or (true?    x) (false?  x)))
     ;; (defn uri?              [x])
     (defn ^boolean indexed?    [x] (satisfies?  IIndexed            x))
     (defn ^boolean named?      [x] (implements? INamed              x))
     (defn ^boolean editable?   [x] (implements? IEditableCollection x))
     (defn ^boolean derefable?  [x] (satisfies?  IDeref              x))
     ;; (defn throwable?        [x])
     ;; (defn exception?        [x])
     (defn ^boolean      error? [x] (instance?   js/Error             x))
     (defn ^boolean       atom? [x] (instance?   Atom                 x))
     (defn ^boolean  transient? [x] (instance?   ITransientCollection x))
     (defn ^boolean   lazy-seq? [x] (instance?   LazySeq              x))
     (defn ^boolean re-pattern? [x] (instance?   js/RegExp            x))

     (defn ^boolean simple-ident?      [x] (and (ident?   x) (nil? (namespace x))))
     (defn ^boolean qualified-ident?   [x] (and (ident?   x)       (namespace x) true))
     (defn ^boolean simple-symbol?     [x] (and (symbol?  x) (nil? (namespace x))))
     (defn ^boolean qualified-symbol?  [x] (and (symbol?  x)       (namespace x) true))
     (defn ^boolean simple-keyword?    [x] (and (keyword? x) (nil? (namespace x))))
     (defn ^boolean qualified-keyword? [x] (and (keyword? x)       (namespace x) true))

     (defn ^boolean nempty-str? [x] (and (string? x) (not (= x ""))))
     (defn ^boolean nblank-str? [x] (and (string? x) (not (str/blank? x))))
     (defn ^boolean nblank?     [x]                  (not (str/blank? x)))
     (defn ^boolean vec2?       [x] (and (vector? x) (= (count x) 2)))
     (defn ^boolean vec3?       [x] (and (vector? x) (= (count x) 3)))))

#?(:clj
   (do
     (defn nneg?           [x] (not (neg? x)))
     (defn zero-num?       [x] (= x 0))
     ;; (defn regular-num? [x])

     (defn float? [x] (or (instance? Double x) (instance? Float x)))
     (defn int?   [x]
       (or
         (instance? Long    x)
         (instance? Integer x)
         ;; (instance? clojure.lang.BigInt x)
         ;; (instance? BigInteger          x)
         (instance? Short x)
         (instance? Byte  x)))

     (defn nat-num?   [x] (and (number? x) (not (neg? x))))
     (defn pos-num?   [x] (and (number? x)      (pos? x)))
     (defn neg-num?   [x] (and (number? x)      (neg? x)))

     (defn nat-int?   [x] (and (int? x) (not (neg? x))))
     (defn pos-int?   [x] (and (int? x)      (pos? x)))
     (defn neg-int?   [x] (and (int? x)      (neg? x)))

     (defn nat-float? [x] (and (float? x) (not (neg? x))))
     (defn pos-float? [x] (and (float? x)      (pos? x)))
     (defn neg-float? [x] (and (float? x)      (neg? x)))

     (defn udt?       [x] (and (int? x) (not (neg? x))))

     (defn pnum? [x] (and (number? x) (let [n (double x)] (and (>= n  0.0) (<= n  1.0)))))
     (defn rnum? [x] (and (number? x) (let [n (double x)] (and (>= n -1.0) (<= n +1.0))))))

   :cljs
   (do
     (defn ^boolean nneg?        [x] (not (neg? x)))
     (defn ^boolean zero-num?    [x] (= x 0))
     (defn ^boolean regular-num? [x]
       (and
         (number? x)
         (not ^boolean (js/isNaN x))
         (not (identical? x js/Infinity))))

     (defn ^boolean float? [x]
       (and
         (number? x)
         (not ^boolean (js/isNaN x))
         (not (identical? x js/Infinity))
         (not (== (js/parseFloat x) (js/parseInt x 10)))))

     (defn ^boolean int? [x]
       (and
         (number? x)
         (not ^boolean (js/isNaN x))
         (not (identical? x js/Infinity))
         (== (js/parseFloat x) (js/parseInt x 10))))

     (defn ^boolean nat-num?   [x] (and (number? x) (not (neg? x))))
     (defn ^boolean pos-num?   [x] (and (number? x)      (pos? x)))
     (defn ^boolean neg-num?   [x] (and (number? x)      (neg? x)))

     (defn ^boolean nat-int?   [x] (and (int? x) (not (neg? x))))
     (defn ^boolean pos-int?   [x] (and (int? x)      (pos? x)))
     (defn ^boolean neg-int?   [x] (and (int? x)      (neg? x)))

     (defn ^boolean nat-float? [x] (and (float? x) (not (neg? x))))
     (defn ^boolean pos-float? [x] (and (float? x)      (pos? x)))
     (defn ^boolean neg-float? [x] (and (float? x)      (neg? x)))

     (defn ^boolean udt?       [x] (and (int? x) (not (neg? x))))

     (defn ^boolean pnum? [x] (and (number? x) (let [n (double x)] (and (>= n  0.0) (<= n  1.0)))))
     (defn ^boolean rnum? [x] (and (number? x) (let [n (double x)] (and (>= n -1.0) (<= n +1.0)))))))

(compile-if have-core-async?
  (let [c ; Silly work-around for edge case described at `have-core-async`?
        (delay
          #?(:cljs cljs.core.async.impl.channels.ManyToManyChannel
             :clj
             (do
               (require       'clojure.core.async)
               (Class/forName "clojure.core.async.impl.channels.ManyToManyChannel"))))]

    #?(:clj  (defn          chan? [x] (instance? @c x))
       :cljs (defn ^boolean chan? [x] (instance? @c x))))
  (do        (defn          chan? [x] nil)))

(do
  ;; ClojureScript keywords aren't `identical?` and Clojure doesn't have
  ;; `keyword-identical?`. This util helps alleviate the pain of writing
  ;; cross-platform code, Ref. http://goo.gl/be8CGP
  #?(:clj  (defalias     kw-identical?         identical?)
     :cljs (def ^boolean kw-identical? keyword-identical?)))

;;;; Type coercions

(do
  ;; (defn not-blank     [s] (if (str/blank? s) nil s))
  ;; (defn not-empty-str [s] (if #?(:clj (.isEmpty ^String s) :cljs (= s "")) nil s))

  (defn as-?nzero  [x] (when (number?  x) (if (zero? x)      nil x)))
  (defn as-?nblank [x] (when (string?  x) (if (str/blank? x) nil x)))
  (defn as-?kw     [x] (cond (keyword? x)       x  (string? x) (keyword x)))
  (defn as-?name   [x] (cond (named?   x) (name x) (string? x)          x))
  (defn as-?qname  [x]
    (cond
      (named?  x) (let [n (name x)] (if-let [ns (namespace x)] (str ns "/" n) n))
      (string? x) x))

  (defn as-?nempty-str [x]
    (when (string? x)
      (if #?(:clj (.isEmpty ^String x) :cljs (= x "")) nil x)))

  (defn as-?nblank-trim [x]
    (when (string? x)
      (let [s (str/trim x)]
        (if #?(:clj (.isEmpty ^String s) :cljs (= s "")) nil s))))

  (comment (as-?nblank-trim " foo  "))

  (defn as-?int #_as-?long [x]
    (cond (number? x) (long x)
          (string? x)
          #?(:cljs (let [x (js/parseInt x 10)] (when-not (js/isNaN x) x))
             :clj
             (try (Long/parseLong x)
                  (catch NumberFormatException _
                    (try (long (Float/parseFloat x))
                         (catch NumberFormatException _ nil)))))))

  (defn as-?float #_as-?double [x]
    (cond (number? x) (double x)
          (string? x)
          #?(:cljs (let [x (js/parseFloat x)] (when-not (js/isNaN x) x))
             :clj  (try (Double/parseDouble x)
                        (catch NumberFormatException _ nil)))))

  (defn as-?udt       [x] (when-let [n (as-?int   x)] (when-not (neg? ^long   n) n)))
  (defn as-?nat-int   [x] (when-let [n (as-?int   x)] (when-not (neg? ^long   n) n)))
  (defn as-?pos-int   [x] (when-let [n (as-?int   x)] (when     (pos? ^long   n) n)))
  (defn as-?nat-float [x] (when-let [n (as-?float x)] (when-not (neg? ^double n) n)))
  (defn as-?pos-float [x] (when-let [n (as-?float x)] (when     (pos? ^double n) n)))

  (defn as-?pnum      [x] (when-let [^double f (as-?float x)] (if (> f 1.0) 1.0 (if (< f  0.0)  0.0 f))))
  (defn as-?rnum      [x] (when-let [^double f (as-?float x)] (if (> f 1.0) 1.0 (if (< f -1.0) -0.0 f))))

  (defn as-?bool [x]
    (cond
      (nil? x) nil
      (or (true? x) (false? x)) x
      (or (= x 0) (= x "false") (= x "FALSE") (= x "0")) false
      (or (= x 1) (= x "true")  (= x "TRUE")  (= x "1")) true))

  ;; Uses simple regex to test for basic "x@y.z" form:
  (let [regex #"^[^\s@]+@[^\s@]+\.\S*[^\.]$"]
    (defn as-?email
      ([        ?s] (as-?email 320 ?s))
      ([max-len ?s] (when-let [s (and ?s (str/trim ?s))]
                      (when (<= (count s) ^long max-len)
                        (re-find regex s))))))

  (defn as-?nemail
    ([        ?s] (when-let [email (as-?email         ?s)] (str/lower-case email)))
    ([max-len ?s] (when-let [email (as-?email max-len ?s)] (str/lower-case email))))

  (comment
    (do  (as-?nemail 11 "FOO@bar.com"))
    (mapv as-?nemail
      ["foo" "foo@" "foo@bar" "Foo@BAR.com"
       "foo@@bar.com" "foo@bar.com." "foo.baz@bar.com"])))

(defn- try-pred [pred x] (catching (pred x) _ false))
(defn #?(:clj when? :cljs ^boolean when?) [pred x] (when (try-pred pred x) x))
(defn is! "Cheaper `have!` that provides less diagnostic info."
  ([     x           ] (is! identity x nil)) ; Nb different to single-arg `have`
  ([pred x           ] (is! identity x nil))
  ([pred x fail-?data]
   (if (try-pred pred x)
     x
     (throw
       (ex-info (str "`is!` " (str pred) " failure against arg: " (pr-str x))
         {:given x :type (type x) :fail-?data fail-?data})))))

(comment [(is! false) (when-let [n (when? nneg? (as-?int 37))] n)])

(defn -as-throw [as-name x]
  (throw (ex-info (str "`as-" (name as-name) "` failed against: `" (pr-str x) "`")
           {:given x :type (type x)})))

(do
  (defn as-nzero             [x] (or (as-?nzero       x) (-as-throw :nzero       x)))
  (defn as-nblank            [x] (or (as-?nblank      x) (-as-throw :nblank      x)))
  (defn as-nblank-trim       [x] (or (as-?nblank-trim x) (-as-throw :nblank-trim x)))
  (defn as-nempty-str        [x] (or (as-?nempty-str  x) (-as-throw :nempty-str  x)))
  (defn as-kw                [x] (or (as-?kw          x) (-as-throw :kw          x)))
  (defn as-name              [x] (or (as-?name        x) (-as-throw :name        x)))
  (defn as-qname             [x] (or (as-?qname       x) (-as-throw :qname       x)))

  (defn as-email
    ([  x] (or (as-?email   x) (-as-throw :email x)))
    ([n x] (or (as-?email n x) (-as-throw :email x))))

  (defn as-nemail
    ([  x] (or (as-?nemail   x) (-as-throw :nemail x)))
    ([n x] (or (as-?nemail n x) (-as-throw :nemail x))))

  (defn as-udt         ^long [x] (or (as-?udt         x) (-as-throw :udt         x)))
  (defn as-int         ^long [x] (or (as-?int         x) (-as-throw :int         x)))
  (defn as-nat-int     ^long [x] (or (as-?nat-int     x) (-as-throw :nat-int     x)))
  (defn as-pos-int     ^long [x] (or (as-?pos-int     x) (-as-throw :pos-int     x)))
  (defn as-float     ^double [x] (or (as-?float       x) (-as-throw :float       x)))
  (defn as-nat-float ^double [x] (or (as-?nat-float   x) (-as-throw :nat-float   x)))
  (defn as-pos-float ^double [x] (or (as-?pos-float   x) (-as-throw :pos-float   x)))
  (defn as-pnum      ^double [x] (or (as-?pnum        x) (-as-throw :pnum        x)))
  (defn as-rnum      ^double [x] (or (as-?rnum        x) (-as-throw :rnum        x)))
  (defn as-bool              [x] (let [?b (as-?bool   x)] (if-not (nil? ?b) ?b (-as-throw :bool x)))))

;;;; Validation

(defmacro check-some
  "Returns first logical false/throwing expression (id/form), or nil."
  ([test & more] `(or ~@(map (fn [test] `(check-some ~test)) (cons test more))))
  ([test       ]
   (let [[error-id test] (if (vector? test) test [nil test])]
     `(let [[test# err#] (catching [~test nil] err# [nil err#])]
        (when-not test# (or ~error-id '~test :check/falsey))))))

(defmacro check-all
  "Returns all logical false/throwing expressions (ids/forms), or nil."
  ([test       ] `(check-some ~test))
  ([test & more]
   `(let [errors# (filterv identity
                    [~@(map (fn [test] `(check-some ~test)) (cons test more))])]
      (not-empty errors#))))

(comment
  (check-some false [:bad-type (string? 0)] nil [:blank (str/blank? 0)])
  (check-all  false [:bad-type (string? 0)] nil [:blank (str/blank? 0)]))

;;;; Keywords

(defn explode-keyword [k] (str/split (as-qname k) #"[\./]"))
(comment (explode-keyword :foo.bar/baz))

(defn merge-keywords
  ([ks            ] (merge-keywords ks false))
  ([ks omit-slash?]
   (when (seq ks)
     (let [parts
           (reduce
             (fn [acc in]
               (if (nil? in)
                 acc
                 (reduce conj acc (explode-keyword in))))
             [] ks)]

       (when (seq parts)
         (if omit-slash?
           (keyword (str/join "." parts))
           (let [ppop (pop parts)]
             (keyword (when (seq ppop) (str/join "." ppop))
               (peek parts)))))))))

(comment (merge-keywords [:foo.bar nil "d.e/k" :baz.qux/end nil] true))

;;;; Bytes

#?(:clj
   (do
     (def ^:const bytes-class (Class/forName "[B"))
     (defn bytes? [x] (instance? bytes-class x)) ; Also introduced in Clojure v1.9-alpha5+
     (defn ba= [^bytes x ^bytes y] (java.util.Arrays/equals x y))

     (defn ba-concat ^bytes [^bytes ba1 ^bytes ba2]
       (let [s1  (alength ba1)
             s2  (alength ba2)
             out (byte-array (+ s1 s2))]
         (System/arraycopy ba1 0 out 0  s1)
         (System/arraycopy ba2 0 out s1 s2)
         out))

     (defn ba-split [^bytes ba ^long idx]
       (if (zero? idx)
         [nil ba]
         (let [s (alength ba)]
           (when (> s idx)
             [(java.util.Arrays/copyOf      ba idx)
              (java.util.Arrays/copyOfRange ba idx s)]))))

     (comment
       (String. (ba-concat (.getBytes "foo") (.getBytes "bar")))
       (let [[x y] (ba-split (.getBytes "foobar") 5)] [(String. x) (String. y)]))

     (declare reduce-n)
     (defn const-ba=
       "Constant-time `ba=`.
       Useful to prevent timing attacks, etc."
       [ba1 ba2]
       (when (and ba1 ba2)
         (let [bax (byte-array [0 1])
               ^bytes ba1 ba1
               ^bytes ba2 ba2
               l1 (alength ba1)
               l2 (alength ba2)
               lmax (max l1 l2)
               lmin (min l1 l2)]

           (reduce-n
             (fn [acc ^long idx]
               (if (>= idx lmin)
                 (and (== (aget bax   0) (aget bax   1)) acc)
                 (and (== (aget ba1 idx) (aget ba2 idx)) acc)))
             true
             lmax))))))

(comment (const-ba= (byte-array [1 2 3 4]) (byte-array [])))

;;;; Reduce

(defn   convey-reduced [x] (if (reduced? x) (reduced x) x)) ; Double-wrap
(defn preserve-reduced "As `core/preserving-reduced`."
  [rf]
  (fn [acc in]
    (let [result (rf acc in)]
      (if (reduced? result)
        (reduced result)
        result))))

(defn reduce-kvs
  "Like `reduce-kv` but takes a flat sequence of kv pairs."
  [rf init kvs]
  (transduce (partition-all 2)
    (completing (fn [acc [k v]] (rf acc k v))) init kvs))

;; No longer so interesting with Clojure 1.7+
(defn reduce-n
  ([rf init       end     ] (reduce rf init (range       end)))
  ([rf init start end     ] (reduce rf init (range start end)))
  ([rf init start end step] (reduce rf init (range start end step))))

(comment (reduce-n conj [] 100 10 -1))

(declare counter)
(defn reduce-indexed
  "Like `reduce` but takes (rf [acc idx in]) with idx as in `map-indexed`.
    As `reduce-kv` against vector coll, but works on any seqable coll type."
  [rf init coll]
  (let [c (counter)]
    (reduce (fn [acc in] (rf acc (c) in)) init coll)))

(comment
  (reduce-indexed (fn [acc idx in] (assoc acc idx in)) {} [:a :b :c])
  (reduce-kv      (fn [acc idx in] (assoc acc idx in)) {} [:a :b :c]))

#?(:cljs
   (defn reduce-obj "Like `reduce-kv` but for JavaScript objects."
     [f init o]
     (reduce (fn [acc k] (f acc k (gobj/get o k nil))) init (js-keys o))))

(do
           (defn run!     [proc coll] (reduce     #(proc %2)    nil coll) nil)
           (defn run-kv!  [proc    m] (reduce-kv  #(proc %2 %3) nil    m) nil)
           (defn run-kvs! [proc  kvs] (reduce-kvs #(proc %2 %3) nil  kvs) nil)
  #?(:cljs (defn run-obj! [proc  obj] (reduce-obj #(proc %2 %3) nil  obj) nil)))

(do ; Faster `reduce`-based variants
  (defn rsome      [pred coll] (reduce    (fn [acc in]  (when-let [p (pred in)]  (reduced p)))     nil coll))
  (defn rsome-kv   [pred coll] (reduce-kv (fn [acc k v] (when-let [p (pred k v)] (reduced p)))     nil coll))
  (defn rfirst     [pred coll] (reduce    (fn [acc in]  (when        (pred in)   (reduced in)))    nil coll))
  (defn rfirst-kv  [pred coll] (reduce-kv (fn [acc k v] (when        (pred k v)  (reduced [k v]))) nil coll))
  (defn revery?    [pred coll] (reduce    (fn [acc in]  (if (pred in)  true (reduced false))) true coll))
  (defn revery-kv? [pred coll] (reduce-kv (fn [acc k v] (if (pred k v) true (reduced false))) true coll))
  (defn revery     [pred coll] (reduce    (fn [acc in]  (if (pred in)  coll (reduced nil))) coll coll))
  (defn revery-kv  [pred coll] (reduce-kv (fn [acc k v] (if (pred k v) coll (reduced nil))) coll coll)))

(comment
  ;; Note that `(every? even? nil)` ≠ `(revery even? nil)`
  [(every? even? nil) (revery even? nil)]
  (qb 1e4
    (rsome #(when (string? %) %) [:a :b :c :d "boo"])
    (rfirst        string?       [:a :b :c :d "boo"])))

;;;; Math

(def ^:const max-long #?(:clj Long/MAX_VALUE :cljs  9007199254740991))
(def ^:const min-long #?(:clj Long/MIN_VALUE :cljs -9007199254740991))

(defn #?(:clj approx== :cljs ^boolean approx==)
  ([      x y] (< (Math/abs (- (double x) (double y))) 0.001))
  ([signf x y] (< (Math/abs (- (double x) (double y))) (double signf))))

(comment (qb 1e5 (approx== 0.01 3.141592 (/ 22 7))))

;; This must reflect to output correct long/double types:
(defn clamp [nmin nmax n] (if (< n nmin) nmin (if (> n nmax) nmax n)))

(do ; These will pass primitives through w/o reflection
  (defmacro <=*    [x y z]       `(let [y# ~y] (and (<= ~x y#) (<= y# ~z))))
  (defmacro >=*    [x y z]       `(let [y# ~y] (and (>= ~x y#) (>= y# ~z))))
  (defmacro <*     [x y z]       `(let [y# ~y] (and (<  ~x y#) (<  y# ~z))))
  (defmacro >*     [x y z]       `(let [y# ~y] (and (>  ~x y#) (>  y# ~z))))
  (defmacro min*   [n1 n2]       `(let [n1# ~n1 n2# ~n2] (if (> n1# n2#) n2# n1#)))
  (defmacro max*   [n1 n2]       `(let [n1# ~n1 n2# ~n2] (if (< n1# n2#) n2# n1#)))
  (defmacro clamp* [nmin nmax n] `(let [nmin# ~nmin nmax# ~nmax n# ~n]
                                    (if (< n# nmin#) nmin# (if (> n# nmax#) nmax# n#)))))

(defn pow [n exp] (Math/pow n exp))
(defn abs [n]     (if (neg? n) (- n) n)) ; #?(:clj (Math/abs n)) reflects
(defn round* ; round
  ([             n] (round* :round nil n))
  ([type         n] (round* type   nil n))
  ([type nplaces n]
   (let [n        (double n)
         modifier (when nplaces (Math/pow 10.0 nplaces))
         n*       (if-not modifier n (* n ^double modifier))
         rounded
         (case type
           ;;; Note same API for both #?(:clj _ :cljs: _)
           :round (Math/round n*) ; Round to nearest int or nplaces
           :floor (Math/floor n*) ; Round down to -inf
           :ceil  (Math/ceil  n*) ; Round up to +inf
           :trunc (long n*)       ; Round up/down toward zero
           (throw (ex-info "Unrecognized round type" {:given type})))]
     (if-not modifier
       (long rounded)                        ; Returns long
       (/ (double rounded) ^double modifier) ; Returns double
       ))))

(comment
  [(round* :floor -1.5)
   (round* :trunc -1.5)
   (round* :floor 5 1.1234567)
   (round* :round 5 1.1234567)])

(do ; Optimized common cases
  (defn round0   ^long [n]            (Math/round    (double n)))
  (defn round1 ^double [n] (/ (double (Math/round (* (double n)  10.0)))  10.0))
  (defn round2 ^double [n] (/ (double (Math/round (* (double n) 100.0))) 100.0))
  (defn perc     ^long [n divisor] (Math/round (* (/ (double n) (double divisor)) 100.0))))

(defn exp-backoff "Returns binary exponential backoff value for n<=36."
  ([^long n-attempt] (exp-backoff n-attempt nil))
  ([^long n-attempt {:keys [min max factor] :or {factor 1000}}]
   (let [n (if (> n-attempt 36) 36 n-attempt) ; >2^36 excessive
         b (Math/pow 2 n)
         t (long (* (+ b ^double (rand b)) 0.5 (double factor)))
         t (long (if min (if (< t ^long min) min t) t))
         t (long (if max (if (> t ^long max) max t) t))]
     t)))

(comment (exp-backoff 128))

(defn chance [p] (< ^double (rand) (double p)))

(comment (chance 0.25))

;;;; Misc

;; js/foo      - `foo` in global object/ns (depends on *target*)
;; js/window   - `window` object: global ns in browsers
;; js/global   - `global` object: global ns in Node.js, etc.?
;; goog/global - Closure's environment-agnostic global object
;;
#?(:cljs (def node-target? (= *target* "nodejs")))
#?(:cljs (def js-?win (when (exists? js/window) js/window)))

(defn force-ref "Like `force` for refs." [x] (if (derefable? x) (deref x) x))
(defn merge-meta   [x m] (with-meta x (merge (meta x) m)))
(defn without-meta [x] (if (meta x) (with-meta x nil) x))

(defn #?(:clj some= :cljs ^boolean some=)
  ([x y]        (and (some? x) (= x y)))
  ([x y & more] (and (some? x) (= x y) (revery? #(= % x) more))))

(comment (some= :foo :foo nil))

(defn nnil "Returns first non-nil arg, or nil."
  ([            ] nil)
  ([x           ] x)
  ([x y         ] (if (nil? x) y x))
  ([x y z       ] (if (nil? x) (if (nil? y) z y) x))
  ([x y z & more] (if (nil? x) (if (nil? y) (if (nil? z) (rfirst some? more) z) y) x)))

(comment
  (qb 1e6
    (or   nil nil nil false :a)
    (nnil nil nil nil false :a)))

(defn parse-version [x]
  (let [[s-version ?s-qualifier] (str/split (str x) #"-" 2)]
    {:version   (when-let [s (re-seq #"\d+" s-version)] (mapv as-?int s))
     :qualifier (when-let [s ?s-qualifier] (str/lower-case s))}))

(comment [(parse-version "40.32.34.8-foo") (parse-version 10.3)])

(defn assert-min-encore-version
  "Version check for dependency conflicts, etc."
  [min-version]
  (let [[xc yc zc] encore-version
        [xm ym zm] (if (vector? min-version) min-version (:version (parse-version min-version)))
        [xm ym zm] (mapv #(or % 0) [xm ym zm])]

    (when-not (or (> xc xm) (and (= xc xm) (or (> yc ym) (and (= yc ym) (>= zc zm)))))
      (throw
        (ex-info "Insufficient `com.taoensso/encore` version, you may have a dependency conflict: see http://goo.gl/qBbLvC for solutions."
          {:min-version  (str/join "." [xm ym zm])
           :your-version (str/join "." [xc yc zc])})))))

(comment (assert-min-encore-version 3.10))

;;;; Collections

#?(:clj  (defn          queue? [x] (instance? clojure.lang.PersistentQueue x))
   :cljs (defn ^boolean queue? [x] (instance?    cljs.core.PersistentQueue x)))

(defn queue "Returns a PersistentQueue."
  ([coll] (into (queue) coll))
  ([] #?(:clj  clojure.lang.PersistentQueue/EMPTY
         :cljs    cljs.core.PersistentQueue.EMPTY)))

(defn queue* [& items] (queue items))
(defn ensure-vec [x] (if (vector? x) x (vec x)))
(defn ensure-set [x] (if (set?    x) x (set x)))

#?(:cljs (defn oset [o k v] (gobj/set (if (nil? o) (js-obj) o) (name k) v)))
#?(:cljs
(defn oget "Like `get` for JS objects, Ref. https://goo.gl/eze8hY."
  ([  k          ] (gobj/get js/window (name k)))
  ([o k          ] (gobj/get o         (name k) nil))
  ([o k not-found] (gobj/get o         (name k) not-found))))

#?(:cljs
   (let [sentinel (js-obj)]
     ;; Could also use `gobg/getValueByKeys`
     (defn oget-in "Like `get-in` for JS objects."
       ([  ks] (oget-in js/window ks nil))
       ([o ks] (oget-in o         ks nil))
       ([o ks not-found]
        (loop [o o
               ks (seq ks)]
          (if ks
            (let [o (gobj/get o (name (first ks)) sentinel)]
              (if (identical? o sentinel)
                not-found
                (recur o (next ks))))
            o))))))

(do
  (defn conj-some "Conjoins each non-nil value."
    ([             ] [])
    ([coll         ] coll)
    ([coll x       ] (if (nil? x) coll (conj coll x)))
    ([coll x & more] (reduce conj-some (conj-some coll x) more)))

  (defn conj-when "Conjoins each truthy value."
    ([             ] [])
    ([coll         ] coll)
    ([coll x       ] (if x (conj coll x) coll))
    ([coll x & more] (reduce conj-when (conj-when coll x) more))))

(comment (conj-some [] :a :b nil :c :d nil false :e))

(do
  (defn assoc-some "Assocs each kv iff its value is not nil."
    ([m k v      ] (if (nil? v) (if (nil? m) {} m) (assoc m k v)))
    ([m k v & kvs]
     (reduce-kvs
       (fn [m k v] (if (nil? v) m (assoc m k v)))
       (assoc-some m k v)
       kvs))

    ([m kvs]
     (reduce-kv
       (fn [m k v] (if (nil? v) m (assoc m k v)))
       (if (nil? m) {} m)
       kvs)))

  (defn assoc-when "Assocs each kv iff its val is truthy."
    ([m k v      ] (if-not v (if (nil? m) {} m) (assoc m k v)))
    ([m k v & kvs]
     (reduce-kvs
       (fn [m k v] (if-not v m (assoc m k v)))
       (assoc-when m k v)
       kvs))

    ([m kvs]
     (reduce-kv
       (fn [acc k v] (if-not v m (assoc m k v)))
       (if (nil? m) {} m)
       kvs)))

  (defn dis-assoc-some
    "Assocs each kv if its value is not nil, otherwise dissocs it."
    ([m k v      ] (if (nil? v) (if (nil? m) {} (dissoc m k)) (assoc m k v)))
    ([m k v & kvs]
     (reduce-kvs
       (fn [m k v] (if (nil? v) (dissoc m k) (assoc m k v)))
       (assoc-some m k v)
       kvs))

    ([m kvs]
     (reduce-kv
       (fn [m k v] (if (nil? v) (dissoc m k) (assoc m k v)))
       (if (nil? m) {} m)
       kvs)))

  ;; Handy as l>r merge
  (defn assoc-nx "Assocs each kv iff its key doesn't already exist."
    ([m k v] (if (contains? m k) m (assoc m k v)))
    ([m k v & kvs] (reduce-kvs assoc-nx (assoc-nx m k v) kvs))
    ([m kvs]
     (reduce-kv
       (fn [m k v] (if (contains? m k) m (assoc m k v)))
       (if (nil? m) {} m)
       kvs))))

(comment
  (assoc-some {:a :A} :b nil :c :C :d nil :e :E)
  (assoc-some {:a :A} {:b :B :c nil :d :D :e false})
  (dis-assoc-some {:a :A :b :B} {:a :a :b nil})
  (reduce-kv assoc-nx {:a :A} {:a :a :b :b}))

(defn get-subvec
  "Like `subvec` but never throws (snaps to valid start and end indexes)."
  ([v ^long start]
   (let [start (if (< start 0) 0 start)
         vlen  (count v)]
     (if (>= start vlen)
       []
       (subvec v start vlen))))

  ([v ^long start ^long end]
   (let [start (if (< start 0) 0 start)
         vlen  (long (count v))
         end   (if (> end vlen) vlen end)]
     (if (>= start end)
       []
       (subvec v start end)))))

(defn get-subvector
  "Like `get-subvec` but:
    - Takes `length` instead of `end` (index).
    - -ive `start` => index from right of vector."
  ([v ^long start]
   (let [vlen (count v)]
     (if (< start 0)
       (let [start (+ start vlen)
             start (if (< start 0) 0 start)]
         (subvec v start vlen))
       (if (>= start vlen)
         []
         (subvec v start vlen)))))

  ([v ^long start ^long length]
   (if (<= length 0)
     []
     (let [vlen (long (count v))]
       (if (< start 0)
         (let [start (+ start vlen)
               start (if (< start 0) 0 start)
               end   (+ start length)
               end   (if (> end vlen) vlen end)]
           (subvec v start end))

         (let [end (+ start length)
               end (if (> end vlen) vlen end)]
           (if (>= start end)
             []
             (subvec v start end))))))))

(comment
  [(get-subvec    nil 2)
   (get-subvector nil 2)]

  (qb 1e6
    (subvec        [:a :b :c] 1)
    (get-subvec    [:a :b :c] 1)
    (get-subvector [:a :b :c] 1))
  ;; [60.01 63.91 58.6]
  )

(defn vnext        [v] (when (> (count v) 1) (subvec v 1)))
(defn vrest        [v] (if   (> (count v) 1) (subvec v 1) []))
(defn vsplit-last  [v] (let [c (count v)] (when (> c 0) [(when (> c 1) (pop v)) (peek v)])))
(defn vsplit-first [v] (let [c (count v)] (when (> c 0) (let [[v1] v] [v1 (when (> c 1) (subvec v 1))]))))

(comment
  (vsplit-first [:a :b :c])
  (vsplit-last  [:a :b :c]))

(defn- fsplit-last
  "Faster (f (vec (butlast xs)) (last x))."
  [f xs]
  (loop [butlast [] xs xs]
    (let [[x1 & xn] xs]
      (if xn
        (recur (conj butlast x1) xn)
        (f butlast x1)))))

(comment (let [v [:a :b]] (qb 1e6 (fsplit-last vector v) [(butlast v) (last v)])))

(defn takev [n coll] (if (vector? coll) (get-subvector coll 0 n) (into [] (take n) coll)))

(defn #?(:clj distinct-elements? :cljs ^boolean distinct-elements?)
  [x] (or (set? x) (= (count x) (count (ensure-set x)))))

(def seq-kvs "(seq-kvs {:a :A}) => (:a :A)." (partial reduce concat))
(defn mapply "Like `apply` but calls `seq-kvs` on final arg."
  [f & args] (apply f (fsplit-last (fn [xs lx] (concat xs (seq-kvs lx))) args)))

(comment [(seq-kvs {:a :A :b :B}) (mapply str 1 2 3 {:a :A})])

(defn into-all "Like `into` but supports multiple \"from\"s."
  ([to from       ] (into to from))
  ([to from & more]
   (persistent!
     (reduce (fn [acc in] (reduce conj! acc in))
       (transient to)
       (cons from more)))))

(defn repeatedly-into
  "Like `repeatedly` but faster and `conj`s items into given collection."
  [coll ^long n f]
  (if (and (> n 10) (editable? coll))
    (persistent! (reduce-n (fn [acc _] (conj! acc (f))) (transient coll) n))
    (do          (reduce-n (fn [acc _] (conj  acc (f)))            coll  n))))

(comment (repeatedly-into [] 100 (partial rand-nth [1 2 3 4 5 6])))

(defn into!
  ([to       from] (reduce          conj! to from))
  ([to xform from] (transduce xform conj! to from)))

(defn xdistinct
  ([] (distinct)) ; core now has a distinct transducer
  ([keyfn]
   (fn [rf]
     (let [seen_ (volatile! (transient #{}))]
       (fn
         ([]    (rf))
         ([acc] (rf acc))
         ([acc input]
          (let [k (keyfn input)]
            (if (contains? @seen_ k)
              acc
              (do (vswap! seen_ conj! k)
                  (rf acc input))))))))))

(comment (into [] (xdistinct) [1 2 3 1 4 5 2 6 7 1]))

(let [p! persistent!, t transient] ; Note `mapv`-like nil->{} semantics
  (defn invert-map       [m]                 (p! (reduce-kv (fn [m k v] (assoc! m v    k))  (t {}) m)))
  (defn map-keys       [f m]                 (p! (reduce-kv (fn [m k v] (assoc! m (f k) v)) (t {}) m)))
  (defn map-vals       [f m] (if (nil? m) {} (p! (reduce-kv (fn [m k v] (assoc! m k (f v))) (t  m) m))))
  (defn filter-keys [pred m] (if (nil? m) {} (p! (reduce-kv (fn [m k v] (if (pred k) m (dissoc! m k))) (t m) m))))
  (defn filter-vals [pred m] (if (nil? m) {} (p! (reduce-kv (fn [m k v] (if (pred v) m (dissoc! m k))) (t m) m))))
  (defn remove-keys [pred m] (if (nil? m) {} (p! (reduce-kv (fn [m k v] (if (pred k) (dissoc! m k) m)) (t m) m))))
  (defn remove-vals [pred m] (if (nil? m) {} (p! (reduce-kv (fn [m k v] (if (pred v) (dissoc! m k) m)) (t m) m)))))

(defn rename-keys
  "Returns a map like the one given, replacing keys using
  the given {<old-new> <new-key>} replacements."
  [replacements m]
  (persistent!
   (reduce-kv
     (fn [m k v]
       (if-let [rk (replacements k)]
         (assoc! (dissoc! m k) rk v)
         m))
     (transient m)
     m)))

(comment (rename-keys {:a :X} {:a :A :b :B :c :C}))

(defn keys-by
  "Returns {(f x) x} map for xs in `coll`."
  [f coll]
  (persistent!
    (reduce (fn [acc x] (assoc! acc (f x) x))
      (transient {}) coll)))

(comment (keys-by :foo [{:foo 1} {:foo 2}]))

(do
  (defn #?(:clj ks=      :cljs ^boolean ks=)      [ks m] (=             (set (keys m)) (ensure-set ks)))
  (defn #?(:clj ks<=     :cljs ^boolean ks<=)     [ks m] (set/subset?   (set (keys m)) (ensure-set ks)))
  (defn #?(:clj ks>=     :cljs ^boolean ks>=)     [ks m] (set/superset? (set (keys m)) (ensure-set ks)))
  (defn #?(:clj ks-nnil? :cljs ^boolean ks-nnil?) [ks m] (revery?     #(some? (get m %))     ks)))

(comment
  (ks=      #{:a :b} {:a :A :b :B  :c :C})
  (ks<=     #{:a :b} {:a :A :b :B  :c :C})
  (ks>=     #{:a :b} {:a :A :b :B  :c :C})
  (ks-nnil? #{:a :b} {:a :A :b :B  :c nil})
  (ks-nnil? #{:a :b} {:a :A :b nil :c nil}))

(defn update-in
  "Like `core/update-in` but resolves an ambiguity with empty `ks`,
  adds support for `not-found`, `:swap/dissoc` vals."
  ;; Recall no `korks` support due to ambiguity: nil => [] or [nil]
  ([m ks           f] (update-in m ks nil f))
  ([m ks not-found f]
   (if-let [ks-seq (seq ks)]
     (let [k (nth ks 0)]
       (if-let [ks (next ks-seq)]
         (assoc m k (update-in (get m k) ks not-found f))
         (if (kw-identical? f :swap/dissoc)
           (dissoc m k)
           (let [v (f (get m k not-found))]
             (if (kw-identical? v :swap/dissoc)
               (dissoc m k)
               (assoc  m k v))))))
     ;; Resolve nil => [nil] ambiguity in `core/update-in`, `assoc-in`, etc.:
     (f m))))

(comment (update-in {:a :A :b :B} [:a] (fn [_] "boo")))

(defn #?(:clj contains-in? :cljs ^boolean contains-in?)
  ([coll ks k] (contains? (get-in coll ks) k))
  ([coll ks  ]
   (if (seq ks)
     (fsplit-last (fn [ks lk] (contains-in? coll ks lk)) ks)
     false)))

(defn dissoc-in
  ([m ks dissoc-k]        (update-in m ks nil (fn [m]       (dissoc m dissoc-k))))
  ([m ks dissoc-k & more] (update-in m ks nil (fn [m] (apply dissoc m dissoc-k more)))))

(comment
  [(dissoc-in    {:a :A} [] :a)
   (dissoc-in    {:a {:b {:c :C :d :D :e :E}}} [:a :b] :c :e)
   (contains-in? {:a {:b {:c :C :d :D :e :E}}} [:a :b :c])
   (contains-in? {:a {:b {:c :C :d :D :e :E}}} [:a])])

(defn node-paths
  ([          m      ] (node-paths associative? m nil))
  ([node-pred m      ] (node-paths node-pred    m nil))
  ([node-pred m basis]
   (let [basis (or basis [])]
     (persistent!
       (reduce-kv
         (fn [acc k v]
           (if-not (node-pred v)
             (conj! acc (conj basis k v))
             (let [paths-from-basis (node-paths node-pred v (conj basis k))]
               (reduce (fn [acc in] (conj! acc in)) acc paths-from-basis))))
         (transient [])
         m)))))

(comment
  (node-paths associative? {:a1 :A1 :a2 {:b1 :B1 :b2 {:c1 :C1 :c2 :C2}}} [:h])
  (node-paths [:a1 :a2 [:b1 :b2 [:c1 :c2] :b3] :a3 :a4]))

(defn interleave-all "Greedy version of `interleave`."
  ([     ] '())
  ([c1   ] (lazy-seq c1))
  ([c1 c2]
     (lazy-seq
      (let [s1 (seq c1) s2 (seq c2)]
        (cond
         (and s1 s2)
         (cons (first s1) (cons (first s2)
                                (interleave-all (rest s1) (rest s2))))
         s1 s1
         s2 s2))))
  ([c1 c2 & colls]
   (lazy-seq
      (let [ss (filter identity (map seq (conj colls c2 c1)))]
        (concat (map first ss)
                (apply interleave-all (map rest ss)))))))

(comment (interleave-all [:a :b :c] [:A :B :C :D :E] [:1 :2]))

(defn vinterleave-all [c1 c2]
  (loop [v (transient []) s1 (seq c1) s2 (seq c2)]
    (cond
      (and s1 s2)
      (recur (conj! (conj! v (first s1)) (first s2)) (next s1) (next s2))
      s1    (persistent! (reduce conj! v s1))
      s2    (persistent! (reduce conj! v s2))
      :else (persistent! v))))

(comment
  (qb 1e5
    (vec (interleave-all [:a :b :c :d] [:a :b :c :d :e]))
        (vinterleave-all [:a :b :c :d] [:a :b :c :d :e])))

(defmacro new-object [] `(if-cljs (cljs.core/js-obj) (Object.)))

(let [not-found (new-object)]
  (defn -merge-with [nest? f maps]
    (reduce
      (fn [acc in]
        (if (nil? in)
          acc
          (reduce-kv
            (fn rf2 [acc k rv]
              (let [lv (get acc k not-found)]
                (cond
                  (identical? lv not-found)
                  (assoc acc k rv)

                  (kw-identical? rv :swap/dissoc)
                  (dissoc acc k)

                  (and nest? (map? rv) (map? lv))
                  (assoc acc k (reduce-kv rf2 lv rv))

                  :else
                  (let [new-rv (f lv rv)]
                    (if (kw-identical? new-rv :swap/dissoc)
                      (dissoc acc k)
                      (assoc  acc k new-rv))))))
            (or acc {})
            in)))
      nil
      maps)))

(do
  (defn merge "Like `core/merge` but faster, supports `:swap/dissoc` rvals."
    [& maps] (-merge-with false (fn [x y] y) maps))

  (defn merge-with "Like `core/merge-with` but faster, supports `:swap/dissoc` rvals."
    [f & maps] (-merge-with false f maps))

  (defn nested-merge "Like `merge` but does nested merging."
    [& maps] (-merge-with :nest (fn [x y] y) maps))

  (defn nested-merge-with "Like `merge-with` but does nested merging."
    [f & maps] (-merge-with :nest f maps)))

(comment
  [(nested-merge nil nil nil)
   (nested-merge nil nil {})
   (nested-merge
     {:a1 :A1 :b1 :B1  :c1 {:a2 :A2 :b2 {:a3 :A3 :b3 :B3  :d1 :D1 :e1 :E1}}}
     {        :b1 :B1* :c1 {        :b2 {        :b3 :B3* :d1 nil :e1 :swap/dissoc}}}
     nil
     {})]
  [nil {} {:a1 :A1, :b1 :B1*, :c1 {:a2 :A2, :b2 {:a3 :A3, :b3 :B3*, :d1 nil}}}])

;;;; Swap stuff

(do
  (deftype Swapped [newv returnv])
  #?(:clj  (defn          swapped? [x] (instance? Swapped x))
     :cljs (defn ^boolean swapped? [x] (instance? Swapped x)))
  (defn swapped ^Swapped [new-val return-val] (Swapped. new-val return-val))
  (defn swapped-vec [x]
    (if (instance? Swapped x)
      [(.-newv ^Swapped x) (.-returnv ^Swapped x)]
      [x x]))

  (comment (qb 1e6 (.-newv (swapped "foo")))))

(compile-if clojure.lang.IAtom
  (def ^:private ^:const atom-tag 'clojure.lang.IAtom)
  (def ^:private ^:const atom-tag  'clojure.lang.Atom))

(defmacro -if-cas! "Micro optimization, mostly for cljs."
  [atom_ old-val new-val then & [?else]]
  `(if-cljs
     (do (reset! ~atom_ ~new-val) ~then)
     (if (.compareAndSet ~(with-meta atom_ {:tag atom-tag}) ~old-val ~new-val)
       ~then
       ~?else)))

(defn reset!?
  "Atomically swaps value of `atom_` to `val` and returns
  true iff the atom's value actually changed. See also `reset-in!?`."
  [atom_ val]
  (loop []
    (let [old @atom_]
      (-if-cas! atom_ old val
        (if (= old val) false true)
        (recur)))))

(comment (let [a (atom nil)] [(reset!? a "foo") (reset!? a "foo") (reset!? a "bar")]))

(defn -swap-val!
  "Used internally by memoization utils."
  [atom_ k f]
  (loop []
    (let [m0 @atom_
          v1 (f (get m0 k))
          m1 (assoc  m0 k v1)]
      (-if-cas! atom_ m0 m1
        v1
        (recur)))))

(do
  (defn- -swap-k0! [return atom_ f]
    (loop []
      (let [v0  @atom_
            s1  (f v0)
            sw? (instance? Swapped s1)
            v1  (if sw? (.-newv ^Swapped s1) s1)]
        (-if-cas! atom_ v0 v1
          (if sw?
            (.-returnv ^Swapped s1)
            (return v0 v1))
          (recur)))))

  (defn- -reset-k0! [return atom_ v1]
    (loop []
      (let [v0 @atom_]
        (-if-cas! atom_ v0 v1
          (return v0 v1)
          (recur)))))

  (defn- -swap-k1! [return atom_ k not-found f]
    (if (kw-identical? f :swap/dissoc)
      (loop []
        (let [m0 @atom_
              m1 (dissoc m0 k)]
          (-if-cas! atom_ m0 m1
            (return (get m0 k not-found) :swap/dissoc)
            (recur))))

      (loop []
        (let [m0  @atom_
              v0  (get m0 k not-found)
              s1  (f v0)
              sw? (instance? Swapped s1)
              v1  (if sw? (.-newv ^Swapped s1) s1)
              m1  (if (kw-identical? v1 :swap/dissoc)
                    (dissoc m0 k)
                    (assoc  m0 k v1))]
          (-if-cas! atom_ m0 m1
            (if sw?
              (.-returnv ^Swapped s1)
              (return v0 v1))
            (recur))))))

  (defn- -reset-k1! [return atom_ k not-found v1]
    (loop []
      (let [m0 @atom_
            m1 (assoc m0 k v1)]
        (-if-cas! atom_ m0 m1
          (return (get m0 k not-found) v1)
          (recur)))))

  (defn- -swap-kn! [return atom_ ks not-found f]
    (if-let [ks-seq (seq ks)]
      (if (next ks-seq)

        (if (kw-identical? f :swap/dissoc)
          (loop []
            (let [m0 @atom_
                  m1 (fsplit-last (fn [ks lk] (dissoc-in m0 ks lk)) ks)]
              (-if-cas! atom_ m0 m1
                (return (get-in m0 ks not-found) :swap/dissoc)
                (recur))))

          (loop []
            (let [m0  @atom_
                  v0  (get-in m0 ks not-found)
                  s1  (f v0)
                  sw? (instance? Swapped s1)
                  v1  (if sw? (.-newv ^Swapped s1) s1)
                  m1  (if (kw-identical? v1 :swap/dissoc)
                        (fsplit-last (fn [ks lk] (dissoc-in m0 ks lk)) ks)
                        (do                     (assoc-in  m0 ks v1)))]
              (-if-cas! atom_ m0 m1
                (if sw?
                  (.-returnv ^Swapped s1)
                  (return v0 v1))
                (recur)))))

        (-swap-k1! return atom_ (nth ks 0) not-found f))
      (-swap-k0!   return atom_                      f)))

  (defn- -reset-kn! [return atom_ ks not-found v1]
    (if-let [ks-seq (seq ks)]
      (if (next ks-seq)
        (loop []
          (let [m0 @atom_
                m1 (assoc-in m0 ks v1)]
            (-if-cas! atom_ m0 m1
              (return (get-in m0 ks not-found) v1)
              (recur))))

        (-reset-k1! return atom_ (nth ks 0) not-found v1))
      (-reset-k0!   return atom_                      v1))))

(let [return (fn [v0 v1] v1)]
  (defn swap-val!
    "Low-level util, returns <new-key-val> or <swapped-return-val>."
    ([atom_ k           f] (-swap-k1! return atom_ k nil       f))
    ([atom_ k not-found f] (-swap-k1! return atom_ k not-found f))))

(let [return (fn [v0 v1] v0)]
  (defn reset-val!
    "Low-level util, returns <old-key-val>."
    ([atom_ k           val] (-reset-k1! return atom_ k nil       val))
    ([atom_ k not-found val] (-reset-k1! return atom_ k not-found val))))

(let [return (fn [v0 v1] [v0 v1])]
  (defn swap-val!*
    "Low-level util, returns [<old-key-val> <new-key-val>]."
    ([atom_ k           f] (-swap-k1! return atom_ k nil       f))
    ([atom_ k not-found f] (-swap-k1! return atom_ k not-found f))))

(defn pull-val!
  "Removes and returns value mapped to key."
  ([atom_ k          ] (pull-val! atom_ k nil))
  ([atom_ k not-found]
   (let [[v0] (swap-val!* atom_ k not-found :swap/dissoc)]
     v0)))

(let [not-found (new-object)]
  (defn reset-val!?
    "Maps value to key and returns true iff the mapped value changed or
    was created."
    [atom_ k new-val]
    (let [v0 (reset-val! atom_ k not-found new-val)]
      (if (= v0 new-val) false true))))

;;

(let [return (fn [v0 v1] v1)]
  (defn swap-in!
    "Like `swap!` but supports `update-in` semantics,
    returns <new-key-val> or <swapped-return-val>."
    ([atom_              f] (-swap-k0! return atom_              f))
    ([atom_ ks           f] (-swap-kn! return atom_ ks nil       f))
    ([atom_ ks not-found f] (-swap-kn! return atom_ ks not-found f))))

(let [return (fn [v0 v1] v0)]
  (defn reset-in!
    "Like `reset!` but supports `update-in` semantics,
    returns <old-key-val>."
    ([atom_              val] (-reset-k0! return atom_              val))
    ([atom_ ks           val] (-reset-kn! return atom_ ks nil       val))
    ([atom_ ks not-found val] (-reset-kn! return atom_ ks not-found val))))

(let [return (fn [v0 v1] [v0 v1])]
  (defn swap-in!*
    "Like `swap!` but supports `update-in` semantics,
    returns [<old-key-val> <new-key-val>]."
    ([atom_              f] (-swap-k0! return atom_              f))
    ([atom_ ks           f] (-swap-kn! return atom_ ks nil       f))
    ([atom_ ks not-found f] (-swap-kn! return atom_ ks not-found f))))

(comment
  [(let [a_ (atom {:a :A :b :B})] [(swap-in! a_ [  ] (fn [m] (assoc m :c :C))) @a_])
   (let [a_ (atom {:a :A :b :B})] [(swap-in! a_ [  ] (fn [m] (swapped (assoc m :c :C) m))) @a_])
   (let [a_ (atom {:a {:b :B}})]  [(swap-in! a_ [:a] (fn [m] (assoc m :c :C))) @a_])
   (let [a_ (atom {:a {:b :B}})]  [(swap-in! a_ [:a] (fn [m] (swapped (assoc m :c :C) m))) @a_])
   (let [a_ (atom {:a {:b 100}})]  (swap-in! a_ [:a :b] inc)) ; => 101
   (let [a_ (atom {:a {:b :b1 :c :c1} :d :d1})] (swap-in! a_ [:a :c] :swap/dissoc) @a_)]

  [[{:a :A, :b :B, :c :C} {:a :A, :b :B, :c :C}]
   [{:a :A, :b :B} {:a :A, :b :B, :c :C}]
   [{:b :B, :c :C} {:a {:b :B, :c :C}}]
   [{:b :B} {:a {:b :B, :c :C}}]
   101
   {:a {:b :b1}, :d :d1}])

;;;; Instants

(do
  (defmacro now-dt*   [] `(if-cljs           (js/Date.)  (java.util.Date.)))
  (defmacro now-udt*  [] `(if-cljs (.getTime (js/Date.)) (System/currentTimeMillis)))
  (defn  now-dt       [] (now-dt*))
  (defn now-udt ^long [] (now-udt*))

  #?(:clj (defn now-nano ^long [] (System/nanoTime))
     :cljs
     (def now-nano "Uses window context as epoch, Ref. http://goo.gl/mWZWnR"
       (if-let [perf (and (oget js-?win "performance"))]
         ;; Ref. http://goo.gl/fn84us
         (if-let [f (or (oget perf "now")  (oget perf "mozNow") (oget perf "msNow")
                        (oget perf "oNow") (oget perf "webkitNow"))]
           ;; JS call returns millisecs double, accurate to 1/1000th of a ms:
           (fn [] (* 1000000 (long (.call f perf))))
           (fn [] (* 1000000 (now-udt*))))
         (fn []   (* 1000000 (now-udt*))))))

  (defmacro now-nano* [] `(if-cljs (now-nano) (System/nanoTime))))

;;;; Memoization

(defn memoize_
  "Like `core/memoize` but faster, non-racy, and supports invalidation."
  [f]
  #?(:cljs
     (let [cache_ (volatile! {})
           get-sentinel (js-obj)]

       (fn [& xs]
         (let [x1 (first xs)]

           (cond
             (kw-identical? x1 :mem/del)
             (let [xn (next  xs)
                   x2 (first xn)]
               (if (kw-identical? x2 :mem/all)
                 (vreset! cache_ {})
                 (vswap!  cache_ dissoc xn))
               nil)

             (kw-identical? x1 :mem/fresh)
             (let [xn (next xs)
                   v  (apply f xn)] (vswap! cache_ assoc xn v) v)

             :else
             (let [v (get @cache_ xs get-sentinel)]
               (if (identical? v get-sentinel)
                 (let [v (apply f xs)] (vswap! cache_ assoc xs v) v)
                 v)))))))

  #?(:clj
     (let [nil-sentinel (Object.)
           cache_ (java.util.concurrent.ConcurrentHashMap.)]

       (fn
         ([ ] @(or (.get cache_ nil-sentinel)
                   (let [dv (delay (f))]
                     (or (.putIfAbsent cache_ nil-sentinel dv) dv))))

         ([& xs]
          (let [x1 (first xs)]

            (cond
              (kw-identical? x1 :mem/del)
              (let [xn (next  xs)
                    x2 (first xn)]
                (if (kw-identical? x2 :mem/all)
                  (.clear  cache_)
                  (.remove cache_ (or xn nil-sentinel)))
                nil)

              (kw-identical? x1 :mem/fresh)
              @(let [xn (next xs)
                     dv (delay (apply f xn))] (.put cache_ (or xn nil-sentinel) dv) dv)

              :else
              @(or (.get cache_ xs)
                   (let [dv (delay (apply f xs))]
                     (or (.putIfAbsent cache_ xs dv) dv))))))))))

(comment
  (do
    (def foo (memoize_ (fn [& args] [(rand) args])))
    (def f0  (memoize  (fn [])))
    (def f0_ (memoize_ (fn [])))
    (def f1  (memoize  (fn [x] x)))
    (def f1_ (memoize_ (fn [x] x))))

  (qb 1e5 (f0   ) (f0_   )) ; [ 5.53  4.85]
  (qb 1e5 (f1 :x) (f1_ :x)) ; [23.99 17.56]
  )

(defn memoize-last
  "Like `memoize` but only caches the fn's most recent call.
  Great for Reactjs render op caching on mobile devices, etc."
  [f]
  (let [cache_ (atom {})]
    (fn [& args]
      @(or (get @cache_ args)
           (get (swap! cache_
                  (fn [cache]
                    (if (get cache args)
                      cache
                      {args (delay (apply f args))})))
             args)))))

(defmacro -gc-now? []
  `(if-clj
     (<= (java.lang.Math/random) ~(/ 1.0 16000))
     (<=       (.random js/Math) ~(/ 1.0 16000))))

(comment (macroexpand '(-gc-now?)))

(deftype SimpleCacheEntry [delay ^long udt])
(deftype TickedCacheEntry [delay ^long udt ^long tick-lru ^long tick-lfu])

(declare top)
(defn memoize
  "Like `core/memoize` but:
    * Often faster, depending on opts.
    * Prevents race conditions on writes.
    * Supports auto invalidation & gc with `ttl-ms` opt.
    * Supports cache size limit & gc with `cache-size` opt.
    * Supports invalidation by prepending args with `:mem/del` or `:mem/fresh`."

  ([f] (memoize_ f)) ; De-raced, commands

  ;; De-raced, commands, ttl, gc
  ([ttl-ms f]
   (have? pos-int? ttl-ms)
   (let [cache_ (atom nil) ; {<args> <SimpleCacheEntry>}
         latch_ (atom nil) ; Used to pause writes during gc
         ttl-ms (long ttl-ms)]

     (fn [& args]
       (let [a1 (first args)]
         (cond
           (kw-identical? a1 :mem/del)
           (let [argn (next  args)
                 a2   (first argn)]
             (if (kw-identical? a2 :mem/all)
               (reset! cache_ nil)
               (swap!  cache_ dissoc argn))
             nil)

           :else
           (let [instant (now-udt*)]

             (when (-gc-now?)
               (let [latch #?(:clj (CountDownLatch. 1) :cljs nil)]
                 (-if-cas! latch_ nil latch
                   (do
                     (swap! cache_
                       (fn [m]
                         (persistent!
                           (reduce-kv
                             (fn [acc k ^SimpleCacheEntry e]
                               (if (> (- instant (.-udt e)) ttl-ms)
                                 (dissoc! acc k)
                                 acc))
                             (transient (or m {}))
                             m))))

                     #?(:clj (.countDown latch))
                     #?(:clj (reset! latch_ nil))))))

             (let [fresh? (kw-identical? a1 :mem/fresh)
                   args   (if fresh? (next args) args)
                   ^SimpleCacheEntry e
                   (-swap-val! cache_ args
                     (fn [?e]
                       (if (or (nil? ?e) fresh?
                               (> (- instant (.-udt ^SimpleCacheEntry ?e)) ttl-ms))
                         (do
                           #?(:clj (let [l @latch_] (when l (.await ^CountDownLatch l))))
                           (SimpleCacheEntry. (delay (apply f args)) instant))
                         ?e)))]
               @(.-delay e))))))))

  ;; De-raced, commands, ttl, gc, max-size
  ([cache-size ttl-ms f]
   (have? [:or nil? pos-int?] ttl-ms)
   (have? pos-int? cache-size)
   (let [tick_      (atom 0)
         cache_     (atom nil) ; {<args> <TickedCacheEntry>}
         latch_     (atom nil) ; Used to pause writes during gc
         ttl-ms     (long (or ttl-ms 0))
         ttl-ms?    (not (zero? ttl-ms))
         cache-size (long cache-size)]

     (fn [& args]
       (let [a1 (first args)]
         (cond
           (kw-identical? a1 :mem/del)
           (let [argn (next args)
                 a2   (first argn)]
             (if (kw-identical? a2 :mem/all)
               (reset! cache_ nil)
               (swap!  cache_ dissoc argn))
             nil)

           :else
           (let [instant (if ttl-ms? (now-udt*) 0)]
             (when (-gc-now?)
               (let [latch #?(:clj (CountDownLatch. 1) :cljs nil)]
                 (-if-cas! latch_ nil latch
                   (do
                     ;; First prune ttl-expired stuff
                     (when ttl-ms?
                       (swap! cache_
                         (fn [m]
                           (persistent!
                             (reduce-kv
                               (fn [acc k ^TickedCacheEntry e]
                                 (if (> (- instant (.-udt e)) ttl-ms)
                                   (dissoc! acc k)
                                   acc))
                               (transient (or m {}))
                               m)))))

                     ;; Then prune by ascending (worst) tick-sum:
                     (let [snapshot @cache_
                           n-to-gc  (- (count snapshot) cache-size)]

                       (when (> n-to-gc 64)
                         (let [ks-to-gc
                               (top n-to-gc
                                 (fn [k]
                                   (let [e ^TickedCacheEntry (get snapshot k)]
                                     (+ (.-tick-lru e) (.-tick-lfu e))))
                                 (keys snapshot))]

                           (swap! cache_
                             (fn [m]
                               (persistent!
                                 (reduce (fn [acc in] (dissoc! acc in))
                                   (transient (or m {})) ks-to-gc)))))))

                     #?(:clj (.countDown latch))
                     #?(:clj (reset! latch_ nil))))))

             (let [fresh?(kw-identical? a1 :mem/fresh)
                   args  (if fresh? (next args) args)

                   ;;; We always adjust counters, even on reads:
                   ^long tick (swap! tick_ (fn [^long n] (inc n)))
                   ^TickedCacheEntry e
                   (-swap-val! cache_ args
                     (fn [?e]
                       #?(:clj (let [l @latch_] (when l (.await ^CountDownLatch l))))
                       (if (or (nil? ?e) fresh?
                               (> (- instant (.-udt ^TickedCacheEntry ?e)) ttl-ms))
                         (TickedCacheEntry. (delay (apply f args)) instant tick 1)
                         (let [e ^TickedCacheEntry ?e]
                           (TickedCacheEntry. (.-delay e) (.-udt e)
                             tick (inc (.-tick-lfu e)))))))]

               @(.-delay e)))))))))

(comment
  (do
    (def f0 (clojure.core/memoize (fn [& [x]] (if x x (Thread/sleep 600)))))
    (def f1 (memoize              (fn [& [x]] (if x x (Thread/sleep 600)))))
    (def f2 (memoize 5000         (fn [& [x]] (if x x (Thread/sleep 600)))))
    (def f3 (memoize 2 nil        (fn [& [x]] (if x x (Thread/sleep 600)))))
    (def f4 (memoize 2 5000       (fn [& [x]] (if x x (Thread/sleep 600))))))

  (qb 1e5 (f0 :x) (f1 :x) (f2 :x) (f3 :x) (f4 :x))
  ;; [22.43 17.42 62.45 61.78 68.23]

  (let [f0 (clojure.core/memoize (fn [] (Thread/sleep 5) (print "f0\n")))
        f1 (memoize              (fn [] (Thread/sleep 5) (print "f1\n")))]
    (println "---")
    (dotimes [_ 10]
      (future (f1)) ; Never prints >once
      (future (f0)))))

(defn fmemoize
  "Fastest-possible Clj memoize. Non-racy, 0-3 arity only.
  Cljs just passes through to `core/memoize`."
  [f]
  #?(:cljs (cljs.core/memoize f)
     :clj
     ;; Non-racey just as fast as racey, and protects against nils in maps
     (let [cache0_ (java.util.concurrent.atomic.AtomicReference. nil)
           cache1_ (java.util.concurrent.ConcurrentHashMap.)
           cachen_ (java.util.concurrent.ConcurrentHashMap.)]

       (fn
         ([ ]
          @(or
             (.get cache0_)
             (let [dv (delay (f))]
               (if (.compareAndSet cache0_ nil dv)
                 dv
                 (.get cache0_)))))

         ([x]
          @(or
             (.get cache1_ x)
             (let [dv (delay (f x))]
               (or (.putIfAbsent cache1_ x dv) dv))))

         ([x1 x2]
          (let [xs [x1 x2]]
            @(or
               (.get cachen_ xs)
               (let [dv (delay (f x1 x2))]
                 (or (.putIfAbsent cachen_ xs dv) dv)))))

         ([x1 x2 x3]
          (let [xs [x1 x2 x3]]
            @(or
               (.get cachen_ xs)
               (let [dv (delay (f x1 x2 x3))]
                 (or (.putIfAbsent cachen_ xs dv) dv)))))))))

(comment
  (let [m0 (memoize  (fn [& args] (count args)))
        m1 (memoize_ (fn [& args] (count args)))
        m2 (fmemoize (fn [& args] (count args)))]

    [(qb 1e6 (m0)          (m1)          (m2))
     (qb 1e6 (m0 "")       (m1 "")       (m2 ""))
     (qb 1e6 (m0 "" "")    (m1 "" "")    (m2 "" ""))
     (qb 1e6 (m0 "" "" "") (m1 "" "" "") (m2 "" "" ""))])

  [[ 74.16  57.48  54.42]
   [284.42 223.74  62.98]
   [508.04 273.04 102.42]
   [823.37 366.64 120.19]])

;;;; Rate limits

(deftype LimitSpec  [^long n ^long ms])
(deftype LimitEntry [^long n ^long udt0])
(deftype LimitHits  [m worst-sid ^long worst-ms])

(let [limit-spec (fn [n ms] (have? pos-int? n ms) (LimitSpec. n ms))]
  (defn- coerce-limit-specs [x]
    (cond!
      (map?    x) (reduce-kv (fn [acc sid [n ms]] (assoc acc sid (limit-spec n ms))) {} x)
      (vector? x)
      (let [i (volatile! -1)]
        (reduce
          (fn [acc [n ms ?id]] ; ?id for back compatibility
            (assoc acc (or ?id (vswap! i (fn [i] (inc ^long i))))
              (limit-spec n ms))) {} x)))))

(comment (qb 1e5 (coerce-limit-specs [[10 1000] [20 2000]])))

(defn limiter*
  "Experimental. Like `limiter` but returns [<limiter> <state_>]."
  [specs]
  (if (empty? specs)
    [nil (constantly nil)]
    (let [latch_ (atom nil) ; Used to pause writes during gc
          reqs_  (atom nil) ; {<rid> {<sid> <LimitEntry>}}
          specs  (coerce-limit-specs specs) ; {<sid> <LimitSpec>}
          f1
          (fn [rid peek?]
            (let [instant (now-udt*)]

              (when (and (not peek?) (-gc-now?))
                (let [latch #?(:clj (CountDownLatch. 1) :cljs nil)]
                  (-if-cas! latch_ nil latch
                    (do
                      (swap! reqs_
                        (fn [reqs] ; {<rid> <entries>}
                          (persistent!
                            (reduce-kv
                              (fn [acc rid entries]
                                (let [new-entries
                                      (reduce-kv
                                        (fn [acc sid ^LimitEntry e]
                                          (if-let [^LimitSpec s (get specs sid)]
                                            (if (>= instant (+ (.-udt0 e) (.-ms s)))
                                              (dissoc acc sid)
                                              acc)
                                            (dissoc acc sid)))
                                        entries ; {<sid <LimitEntry>}
                                        entries)]
                                  (if (empty? new-entries)
                                    (dissoc! acc rid)
                                    (assoc!  acc rid new-entries))))
                              (transient (or reqs {}))
                              reqs))))

                      #?(:clj (.countDown latch))
                      #?(:clj (reset! latch_ nil))))))

              ;; Need to atomically check if all limits pass before
              ;; committing to any n increments:
              (loop []
                (let [reqs        @reqs_     ; {<sid> <entries>}
                      entries (get reqs rid) ; {<sid> <LimitEntry>}
                      ?hits                  ; ?LimitHits
                      (if (nil? entries)
                        nil
                        (reduce-kv
                          (fn [^LimitHits acc sid ^LimitEntry e]
                            (if-let [^LimitSpec s (get specs sid)]
                              (if (< (.-n e) (.-n s))
                                acc
                                (let [tdelta (- (+ (.-udt0 e) (.-ms s)) instant)]
                                  (if (<= tdelta 0)
                                    acc
                                    (cond
                                      (nil? acc) (LimitHits. {sid tdelta} sid tdelta)

                                      (> tdelta (.-worst-ms acc))
                                      (LimitHits. (assoc (.-m acc) sid tdelta) sid tdelta)

                                      :else
                                      (LimitHits. (assoc (.-m acc) sid tdelta)
                                        (.-worst-sid acc)
                                        (.-worst-ms  acc))))))
                              acc))
                          nil
                          entries))]

                  (if (or peek? ?hits)
                    ;; No action (peeking, or hit >= 1 spec)
                    (when-let [^LimitHits h ?hits]
                      [(.-worst-sid h) (.-worst-ms h) (.-m h)])

                    ;; Passed all limit specs, ready to commit increments:
                    (if-let [l @latch_]
                      #?(:clj (do (.await ^CountDownLatch l) (recur)) :cljs nil)
                      (let [new-entries
                            (reduce-kv
                              (fn [acc sid ^LimitSpec s]
                                (assoc acc sid
                                  (if-let [^LimitEntry e (get entries sid)]
                                    (let [udt0 (.-udt0 e)]
                                      (if (>= instant (+ udt0 (.-ms s)))
                                        (LimitEntry. 1 instant)
                                        (LimitEntry. (inc (.-n e)) udt0)))
                                    (LimitEntry. 1 instant))))
                              entries
                              specs)]

                        (-if-cas! reqs_ reqs (assoc reqs rid new-entries)
                          nil
                          (recur)))))))))]

      [reqs_
       (fn check-limits!
         ([          ] (f1 nil    false))
         ([    req-id] (f1 req-id false))
         ([cmd req-id]
          (cond
            (kw-identical? cmd :rl/reset)
            (do
              (if (kw-identical? req-id :rl/all)
                (reset! reqs_ nil)
                (swap!  reqs_ dissoc req-id))
              nil)

            (kw-identical? cmd :rl/peek)
            (f1 req-id true)

            :else
            (throw
              (ex-info "Unrecognized rate limiter command"
                {:given cmd :req-id req-id})))))])))

(defn limiter ; rate-limiter
  "Takes {<spec-id> [<n-max-reqs> <msecs-window>]}, and returns a rate
  limiter (fn check-limits! [req-id]) -> nil (all limits pass), or
  [<worst-spec-id> <worst-backoff-msecs> {<spec-id> <backoff-msecs>}].

  Limiter fn commands:
    :rl/peek  <req-id> - Check limits w/o side effects.
    :rl/reset <req-id> - Reset all limits for given req-id."
  [specs]
  (let [[_ f] (limiter* specs)]
    f))

(comment
  (def rl1
    (limiter
      {:2s [1 2000]
       :5s [2 5000]
       :1d [5 (ms :days 1)]}))

  (qb 1e6 (rl1)) ; 266.58
  )

;;;; Counters

#?(:clj
   (deftype Counter [^java.util.concurrent.atomic.AtomicLong n_]
     clojure.lang.IDeref (deref [_] (.get n_))
     clojure.lang.IFn
     (invoke [_    ] (.getAndIncrement n_))
     (invoke [_ add] (.getAndAdd       n_ (long add)))
     (invoke [_ action n]
       (let [n (long n)]
         (case action
           (:add)           (do (.addAndGet n_ n) nil)
           (:set)           (do (.set       n_ n))
           (:set= :set-get) (do (.set       n_ n) n)
           (:=set :get-set) (do (.getAndSet n_ n))
           (:=+   :get-add) (do (.getAndAdd n_ n))
           (:+=   :add-get) (do (.addAndGet n_ n))))))

   :cljs
   (deftype Counter [n_]
     IDeref (-deref [_] @n_)
     IFn
     (-invoke [_    ] (let [n @n_] (vswap! n_ (fn [c] (+ c   1))) n))
     (-invoke [_ add] (let [n @n_] (vswap! n_ (fn [c] (+ c add))) n))
     (-invoke [_ action n]
       (case action
         (:add)           (do          (vswap!  n_ (fn [c] (+ c n))) nil)
         (:set)           (do          (vreset! n_ n) nil)
         (:set= :set-get) (do          (vreset! n_ n))
         (:=set :get-set) (let [o @n_] (vreset! n_ n) o)
         (:=+   :get-add) (let [o @n_] (vswap!  n_ (fn [c] (+ c n))) o)
         (:+=   :add-get) (do          (vswap!  n_ (fn [c] (+ c n))))))))

(defn counter
  "Returns a fast atomic Counter with `init` initial int value:
    - (<counter>    ) -> add 1, return old val
    - (<counter> <n>) -> add n, return old val

    Experimental 3-arity version takes an `action`:
      :add, :set, :set-get, :get-set, :get-add, :add-get"
  ([    ] (counter 0))
  ([init]
   #?(:clj  (Counter. (java.util.concurrent.atomic.AtomicLong. init))
      :cljs (Counter. (volatile!                               init)))))

(comment (let [c (counter)] (dotimes [_ 100] (c 2)) (c)))

(defn- rc-deref [^long msecs ts_ n-skip_ gc-fn]
  (let [t1 (now-udt*)
        ^long n-skip0  @n-skip_
        ts             @ts_
        n-total  (count ts)
        ^long n-window
        (reduce
          (fn [^long n ^long t0]
            (if (<= (- t1 t0) msecs)
              (inc n)
              (do  n)))
          0
          (subvec ts n-skip0))

        n-skip1 (- n-total n-window)]

    ;; (println {:n-total n-total :n-window n-window :n-skip0 n-skip0 :n-skip1 n-skip1})
    (when (<            n-skip0 n-skip1)
      (-if-cas! n-skip_ n-skip0 n-skip1
        (when (> n-skip1 10000) ; Time to gc, amortised cost
          (gc-fn n-skip1))))

    n-window))

#?(:clj
   (deftype RollingCounter [^long msecs ts_ n-skip_ p_]
     clojure.lang.IFn
     (invoke [this]
       (when-let [p @p_] @p) ; Block iff latched
       (swap! ts_ (let [t1 (now-udt*)] (fn [v] (conj v t1))))
       this ; Return to allow optional deref
       )

     clojure.lang.IDeref
     (deref [_]
       (when-let [p @p_] @p) ; Block iff latched
       (rc-deref msecs ts_ n-skip_
         (fn gc [n-skip1]
           (let [p (promise)]
             (-if-cas! p_ nil p ; Latch
               (do
                 (swap! ts_ (fn [v] (subvec v n-skip1)))
                 (reset!  n-skip_ 0)
                 (reset!  p_ nil)
                 (deliver p  nil))))))))

   :cljs
   (deftype RollingCounter [^long msecs ts_ n-skip_]
     IFn
     (-invoke [this]
       (swap! ts_ (let [t1 (now-udt*)] (fn [v] (conj v t1))))
       this ; Return to allow optional deref
       )

     IDeref
     (-deref [_]
       (rc-deref msecs ts_ n-skip_
         (fn gc [n-skip1]
           (swap! ts_ (fn [v] (subvec v n-skip1)))
           (reset! n-skip_ 0))))))

(defn rolling-counter
  "Experimental. Returns a RollingCounter that you can:
    - Invoke to increment count in last `msecs` window and return RollingCounter.
    - Deref  to return    count in last `msecs` window."
  [msecs]
  (RollingCounter.
    (long (have pos-int? msecs))
    (atom [])
    (atom 0)
    #?(:clj (atom nil))))

(comment
  (def myrc (rolling-counter 4000))
  (dotimes [_ 100000] (myrc))
  @myrc)

;;;; Strings

#?(:clj  (def ^String system-newline (System/getProperty "line.separator"))
   :cljs (def         system-newline "\n"))

#?(:clj  (defn          str-builder? [x] (instance?            StringBuilder x))
   :cljs (defn ^boolean str-builder? [x] (instance? goog.string.StringBuffer x)))

(def str-builder "For cross-platform string building"
  #?(:clj  (fn (^StringBuilder [      ] (StringBuilder.))
               (^StringBuilder [s-init] (StringBuilder. ^String s-init)))

     :cljs (fn ([      ] (goog.string.StringBuffer.))
               ([s-init] (goog.string.StringBuffer. s-init)))))

(defn sb-append "For cross-platform string building"
  #?(:clj  (^StringBuilder [^StringBuilder str-builder ^String s] (.append str-builder s))
     :cljs (               [               str-builder         s] (.append str-builder s)))
  ([str-builder s & more]
   (sb-append str-builder s)
   (reduce (fn [acc in] (sb-append acc in)) str-builder more)))

(comment (str (sb-append (str-builder "foo") "bar")))

(def str-rf "String builder reducing fn"
  (fn
    ([]       (str-builder))
    ([acc]               (if (str-builder? acc) acc (str-builder (str acc)))) ; cf
    ([acc in] (sb-append (if (str-builder? acc) acc (str-builder (str acc))) (str in)))))

(comment
  (qb 1e3 ; [358.45 34.6]
         (reduce str    (range 512))
    (str (reduce str-rf (range 512)))))

(defn str-join
  "Faster, transducer-based generalization of `clojure.string/join` with `xform`
    support"
  (^String [                coll] (str-join nil       nil coll))
  (^String [separator       coll] (str-join separator nil coll))
  (^String [separator xform coll]
   (if (and separator (not= separator ""))
     (let [sep-xform (interpose separator)
           str-rf*   (completing str-rf str)]
       (if xform
         (transduce (comp xform sep-xform) str-rf* coll)
         (transduce             sep-xform  str-rf* coll)))
     (if xform
       (transduce xform (completing str-rf str) coll)
       (str (reduce str-rf coll))))))

(comment
  (qb 1e5
    (str/join "," ["a" "b" "c" "d"])
    (str-join "," ["a" "b" "c" "d"])
    (str-join ""  ["a" "b" "c" "d"])) ; [29.37 23.63 13.34]
  (str-join "," (comp (filter #{"a" "c"}) (map str/upper-case)) ["a" "b" "c"]))

(defn #?(:clj str-contains? :cljs ^boolean str-contains?)
  [s substr]
  #?(:clj  (.contains ^String s ^String substr)
     :cljs (not= -1 (.indexOf s substr))))

(defn #?(:clj str-starts-with? :cljs ^boolean str-starts-with?)
  [s substr]
  #?(:clj  (.startsWith ^String s ^String substr)
     :cljs (zero? (.indexOf s substr))))

(defn #?(:clj str-ends-with? :cljs ^boolean str-ends-with?)
  [s substr]
  #?(:clj (.endsWith ^String s ^String substr)
     :cljs
     (let [s-len      (.-length s)
           substr-len (.-length substr)]
       (when (>= s-len substr-len)
         (not= -1 (.indexOf s substr (- s-len substr-len)))))))

(defn str-?index
  ([s substr          ] (str-?index s substr 0         false))
  ([s substr start-idx] (str-?index s substr start-idx false))
  ([s substr start-idx last?]
   (let [result
         (if last?
           #?(:clj  (.lastIndexOf ^String s ^String substr ^long start-idx)
              :cljs (.lastIndexOf         s         substr       start-idx))
           #?(:clj  (.indexOf     ^String s ^String substr ^long start-idx)
              :cljs (.indexOf             s         substr       start-idx)))]

     (when (not= result -1) result))))

(comment (qb 1000 (str-?index "hello there" "there")))

(defn get-substr
  "Like `subs` but provides consistent clj/s behaviour and never throws
  (snaps to valid start and end indexes)."
  ([s ^long start]
   #?(:cljs (.substring s start)
      :clj
      (let [start (if (< start 0) 0 start)
            slen  (.length ^String s)]
        (if (>= start slen)
          ""
          (.substring ^String s start slen)))))

  ([s ^long start ^long end]
   #?(:cljs (if (>= start end) "" (.substring s start end))
      :clj
      (let [start (if (< start 0) 0 start)
            slen  (long (.length ^String s))
            end   (if (> end slen) slen end)]
        (if (>= start end)
          ""
          (.substring ^String s start end))))))

(comment
  (get-substr "foo" 1)
  (get-substr "hello world" -10)
  (get-substr "hello world" 100)
  (get-substr "hello world" -10 100)
  (get-substr "hello world" 100 -10)
  (qb 1e5
    (subs       "hello world"   0  11)
    (get-substr "hello world" -10 100)))

(defn get-substring
  "Like `get-substr` but:
    - Takes `length` instead of `end` (index).
    - -ive `start` => index from right of string."
  ([s ^long start]
   #?(:cljs (as-?nempty-str (.substr s start))
      :clj
      (let [slen (.length ^String s)]
        (if (< start 0)
          (let [start (+ start slen)
                start (if (< start 0) 0 start)]
            (.substring ^String s start) slen)
          (if (>= start slen)
            nil
            (.substring ^String s start slen))))))

  ([s ^long start ^long length]
   #?(:cljs (as-?nempty-str (.substr s start length))
      :clj
      (if (<= length 0)
        nil
        (let [slen (long (.length ^String s))]
          (if (< start 0)
            (let [start (+ start slen)
                  start (if (< start 0) 0 start)
                  end   (+ start length)
                  end   (if (> end slen) slen end)]
              (.substring ^String s start end))

            (let [end (+ start length)
                  end (if (> end slen) slen end)]
              (if (>= start end)
                nil
                (.substring ^String s start end)))))))))

(comment
  (get-substring "hello world" -8)
  (get-substring "hello world" -8 2)
  (get-substring "hello world" 2 2))

#?(:clj
   (defn norm-str
     "Given a Unicode string, returns the normalized de/composed form.
     It's often a good idea to normalize strings before exchange or storage,
     especially if you're going to be querying against those string.

     `form` is e/o #{:nfc :nfkc :nfd :nfkd <java.text.NormalizerForm>}.
     Defaults to :nfc as per W3C recommendation."

     ([     s] (norm-str :nfc s))
     ([form s]
      [s]
      (java.text.Normalizer/normalize s
        (case form
          :nfc  java.text.Normalizer$Form/NFC
          :nfkc java.text.Normalizer$Form/NFKC
          :nfd  java.text.Normalizer$Form/NFD
          :nfkd java.text.Normalizer$Form/NFKD
          (if (instance? java.text.Normalizer$Form form)
            form
            (throw
              (ex-info "Unrecognized normalization form"
                {:form form :type (type form)}))))))))

(comment (qb 1e6 (norm-str :nfc "foo"))) ; 114

(defn str-replace
  "Like `str/replace` but provides consistent clj/s behaviour.

  Workaround for http://dev.clojure.org/jira/browse/CLJS-794,
                 http://dev.clojure.org/jira/browse/CLJS-911.

  Note that ClojureScript 1.7.145 introduced a partial fix for CLJS-911.
  A full fix could unfortunately not be introduced w/o breaking compatibility
  with the previously incorrect behaviour. CLJS-794 also remains unresolved."
  [s match replacement]
  #?(:clj (str/replace s match replacement)
     :cljs
     (cond
       (string? match) ; string -> string replacement
       (.replace s (js/RegExp. (gstr/regExpEscape match) "g") replacement)
       ;; (.hasOwnProperty match "source") ; No! Ref. http://goo.gl/8hdqxb

       (instance? js/RegExp match) ; pattern -> string/fn replacement
       (let [flags (str "g" (when (.-ignoreCase match) "i")
                            (when (.-multiline  match) "m")) ; Fix CLJS-794
             replacement ; Fix CLJS-911
             (if (string? replacement)
               replacement
               ;; Note that the merged CLJS-911 fix actually tries to vary
               ;; behaviour here based on the number of matches(!)
               (fn [& args] (replacement (vec args))))]
         (.replace s (js/RegExp. (.-source match) flags) replacement))
       :else (throw (str "Invalid match arg: " match)))))

(do
  (defn nil->str "nil/undefined -> \"nil\"" [x]
    #?(:clj  (if                    (nil? x)  "nil" x)
       :cljs (if (or (undefined? x) (nil? x)) "nil" x)))

  (defn format*
    #?(:clj ^String [fmt args]
       :cljs        [fmt args])
    (let [fmt  (or fmt "") ; Prevent NPE
          args (mapv nil->str args)]
      #?(:clj  (String/format     fmt (to-array args))
         :cljs (apply gstr/format fmt           args))))

  (defn format
    "Like `core/format` but:
      * Returns \"\" when fmt is nil rather than throwing an NPE.
      * Formats nil as \"nil\" rather than \"null\".
      * Provides ClojureScript support via goog.string.format (this has fewer
        formatting options than Clojure's `format`!)."
    [fmt & args] (format* fmt args)))

(defn str-join-once
  "Like `string/join` but skips duplicate separators."
  [separator coll]
  (let [sep separator]
    (if (str/blank? sep)
      (str (reduce str-rf "" coll))
      (let [acc-ends-with-sep?_ (volatile! false)
            acc-empty?_         (volatile! true)]
        (str
          (reduce
            (fn [acc in]
              (let [in (str in)
                    in-empty? (= in "")
                    in-starts-with-sep? (str-starts-with? in sep)
                    in-ends-with-sep?   (str-ends-with?   in sep)
                    acc-ends-with-sep?  @acc-ends-with-sep?_
                    acc-empty?          @acc-empty?_]

                (vreset! acc-ends-with-sep?_ in-ends-with-sep?)
                (when acc-empty? (vreset! acc-empty?_ in-empty?))

                (if acc-ends-with-sep?
                  (if in-starts-with-sep?
                    (sb-append acc (.substring in 1))
                    (sb-append acc in))

                  (if in-starts-with-sep?
                    (sb-append acc in)
                    (if (or acc-empty? in-empty?)
                      (sb-append acc in)
                      (do (sb-append acc sep)
                          (sb-append acc in)))))))
            (str-builder)
            coll))))))

(defn path [& parts] (str-join-once "/" parts))
(comment (path "foo/" nil "/bar" "baz/" "/qux/"))

(defn norm-word-breaks
  "Converts all word breaks of any form and length (including line breaks of any
  form, tabs, spaces, etc.) to a single regular space."
  [s] (str/replace (str s) #"\s+" \space))

(defn count-words [s] (if (str/blank? s) 0 (count (str/split s #"\s+"))))
(comment (count-words "Hello this is a    test"))

(defn uuid-str
  "Returns a UUIDv4 string of form \"xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx\".
  Ref. http://www.ietf.org/rfc/rfc4122.txt,
       https://gist.github.com/franks42/4159427"
  ([max-length] (get-substring (uuid-str) 0 max-length))
  ([]
   #?(:clj (str (java.util.UUID/randomUUID))
      :cljs
      (let [hex  (fn [] (.toString (rand-int 16) 16))
            rhex (.toString (bit-or 0x8 (bit-and 0x3 (rand-int 16))) 16)]
        (str (hex) (hex) (hex) (hex)
             (hex) (hex) (hex) (hex) "-"
             (hex) (hex) (hex) (hex) "-"
             "4"   (hex) (hex) (hex) "-"
             rhex  (hex) (hex) (hex) "-"
             (hex) (hex) (hex) (hex)
             (hex) (hex) (hex) (hex)
             (hex) (hex) (hex) (hex))))))

(comment (qb 1e4 (uuid-str 5)))

(defn into-str
  "Simple Hiccup-like string templating to complement Tempura."
  [& xs]
  (str
    (reduce
      (fn rf [acc in]
        (if (sequential? in)
          (reduce rf acc in)
          (sb-append acc (str in))))
      (str-builder)
      xs)))

(comment
  (let [br "\n\n"]
    (into-str :a :b br :c (for [n (range 5)] [n br])
      (when true [:d :e [:f :g]]))))

;;;; Security, etc.

(defn const-str=
  "Constant-time string equality checker.
  Useful to prevent timing attacks, etc."
  [s1 s2]
  (when (and s1 s2)

    #?(:clj
       (const-ba=
         (.getBytes ^String s1 "UTF-8")
         (.getBytes ^String s2 "UTF-8"))

       :cljs
       (let [vx ["0" "1"]
             v1 (vec   s1)
             v2 (vec   s2)
             n1 (count v1)
             n2 (count v2)
             nmax (max n1 n2)
             nmin (min n1 n2)]

         (reduce-n
           (fn [acc idx]
             (if (>= idx nmin)
               (and (= (get vx   0) (get vx   1)) acc)
               (and (= (get v1 idx) (get v2 idx)) acc)))
           true
           nmax)))))

(comment (const-str= "foo" ""))

(defmacro thread-local-proxy
  [& body] `(proxy [ThreadLocal] [] (initialValue [] (do ~@body))))

#?(:clj
   (compile-if (fn [] (java.security.SecureRandom/getInstanceStrong)) ; Java 8+, blocking
     (def ^:private srng* (thread-local-proxy (java.security.SecureRandom/getInstanceStrong)))
     (def ^:private srng* (thread-local-proxy (java.security.SecureRandom/getInstance "SHA1SRNG")))))

#?(:clj
   (defn secure-rng
     "Returns a thread-local `java.security.SecureRandom`.
     Favours security over performance. Automatically re-seeds occasionally.
     May block while waiting on system entropy!"
     ^java.security.SecureRandom []
     (let [rng ^java.security.SecureRandom (.get ^ThreadLocal srng*)]
       ;; Occasionally supplement current seed for extra security.
       ;; Otherwise an attacker could *theoretically* observe large amounts of
       ;; srng output to determine initial seed, Ref. https://goo.gl/MPM91w
       (when (< (.nextDouble rng) 2.44140625E-4) (.setSeed rng (.generateSeed rng 8)))
       rng)))

(defn secure-rand-bytes
  "Returns `size` random bytes using `secure-rng` or `js/Crypto`."
  #?(:clj ^bytes [size] :cljs [size])
  #?(:clj  (let [ba (byte-array     size)] (.nextBytes (secure-rng)    ba) ba)
     :cljs (let [ba (js/Uint8Array. size)] (.getRandomValues js/Crypto ba) ba)))

(comment
  (qb  1e6 (secure-rand-bytes 21)) ; 1021.07
  (do (seq (secure-rand-bytes 21))))

(def           ^:const nanoid-alphabet "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_")
(def ^:private          parse-alphabet
  "Ref.
    Java impl.: https://bit.ly/3dtYv73,
      JS impl.: https://bit.ly/3fYv1zT,
    Motivation: https://bit.ly/2VhWuEO"
  (fmemoize
    (fn [alphabet len]
      (let [an   (count alphabet)
            len  (long  len)
            _    (when (or (< an 1) (> an 256)) (throw (ex-info "`alphabet`: must be ℕ∈[1,256]" {})))
            _    (when (<= len 0)               (throw (ex-info      "`len`: must be ℕ∈[0,∞)"   {})))
            ;;   (2 << (int) Math.floor(Math.log(alphabet.length - 1) / Math.log(2))) - 1;
            mask (dec (bit-shift-left 2 (int (Math/floor (/ (Math/log (dec an)) (Math/log 2))))))
            ;;   (int) Math.ceil(1.6 * mask * size / alphabet.length);
            step (long (Math/ceil (/ (* (* 1.6 mask) len) an)))]

        [mask step (mapv str alphabet)]))))

(comment (qb 1e6 (parse-alphabet nanoid-alphabet 21)))

(defn secure-rand-id
  "Experimental.
  Given `alphabet` (a string of possible characters), returns a securely
  random string of length `len`.

  Trying to do this the obvious/naive way (by repeatedly generating a secure
  random number and mapping it to an alphabet character with modulo) actually
  introduces bias into ids that can be exploited by an attacker.

  The method used here is designed to eliminate that bias.
  Based on https://bit.ly/3dtYv73."

  #?(:clj [alphabet ^long len] :cljs [alphabet len])
  (let [#?(:clj [^byte mask step v] :cljs [mask step v])
        (parse-alphabet alphabet len)

        an (count v)
        sb (str-builder)]

    (loop []
      (let [ba (secure-rand-bytes step)
            result
            (reduce-n
              (fn [acc idx]
                (let [alpha-idx (bit-and mask (aget ba idx))]
                  (if (>= alpha-idx an)
                    acc ; Out of alphabet range
                    (let [acc (sb-append acc (v alpha-idx))]
                      (if (== (count acc) len)
                        (reduced (str acc))
                        (do           acc))))))
              sb
              step)]
        (if (string? result) result (recur))))))

(let [alphabet (mapv str nanoid-alphabet)
      mask     0x3f]

  (defn nanoid
    "Experimental. Optimized variant of `secure-rand-id` that returns Nano IDs
    as in https://github.com/ai/nanoid."
    ([   ] (nanoid 21))
    ([len]
     (let [ba (secure-rand-bytes len) #_(byte-array [81 -125 -54 -45 -108 99])]
       (str
         (reduce-n
           (fn [acc idx]
             (sb-append acc (alphabet (bit-and mask (aget ba idx)))))
           (str-builder)
           (alength ba)))))))

(comment (qb 1e5 (secure-rand-id nanoid-alphabet 21) (nanoid) (uuid-str))) ; [343.31 205.98 82.86]

;;;; Sorting

#?(:cljs (defn rcompare "Reverse comparator." [x y] (compare y x))
   :clj  (defn rcompare "Reverse comparator."
           {:inline (fn [x y] `(. clojure.lang.Util compare ~y ~x))}
           [x y] (compare y x)))

(defn sortv
  "Like `core/sort` but:
    - Returns a vector.
    - `comparator` can be `:asc`, `:desc`, or an arbitrary comparator.
    - An optional `keyfn` may be provided, as in `core/sort-by`."
  ;; A little faster than `(vec (sort ...))` when `coll` very large
  ([                  coll] (sortv nil :asc       coll))
  ([       comparator coll] (sortv nil comparator coll))
  ([?keyfn comparator coll]
   (if-not (seq coll)
     []
     (let [comparator
           (case comparator
             :asc                    compare
             (:dsc :desc) (fn [x y] (compare y x))
             comparator)

           comparator
           (if-let [kfn (when (not= ?keyfn identity) ?keyfn)]
             (fn [x y] (comparator (kfn x) (kfn y)))
             comparator)

           a (to-array coll)]

       #?(:clj  (java.util.Arrays/sort a ^java.util.Comparator comparator)
          :cljs (garray/stableSort     a (fn->comparator       comparator)))

       (with-meta (vec a) (meta coll))))))

(comment
  (sortv second :desc [[1 10] [2 9] [3 8] [4 7] [5 6]])
  (let [v (vec (range 1e5))] (qb 1e2 (vec (sort v)) (sortv v) (sortv :desc v))))

(let [sentinel (new-object)
      nil->sentinel (fn [x] (if (nil? x) sentinel x))
      sentinel->nil (fn [x] (if (identical? x sentinel) nil x))]

  (defn reduce-top
    "Reduces the top `n` items from `coll` of N items.
    Clj impln is O(N.logn) vs O(N.logN) for (take n (sort-by ...))."
    ([n           rf init coll] (reduce-top n identity compare rf init coll))
    ([n keyfn     rf init coll] (reduce-top n keyfn    compare rf init coll))
    ([n keyfn cmp rf init coll]
     (let [coll-size (count coll)
           n (long (min coll-size (long n)))]

       (if-not (pos? n)
         init
         #?(:cljs ; TODO Real impl.
            (transduce (take n) (completing rf) init
              (sort-by keyfn cmp coll))

            :clj
            (let [pq (java.util.PriorityQueue. coll-size
                       (fn [x y] (cmp (keyfn (sentinel->nil x))
                                      (keyfn (sentinel->nil y)))))]

              (run! #(.offer pq (nil->sentinel %)) coll)
              (reduce-n (fn [acc _] (rf acc (sentinel->nil (.poll pq))))
                init n))))))))

(defn top-into
  "Conjoins the top `n` items from `coll` into `to` using `reduce-top`."
  ([to n           coll] (top-into to n identity compare coll))
  ([to n keyfn     coll] (top-into to n keyfn    compare coll))
  ([to n keyfn cmp coll]
   (if (editable? to)
     (persistent! (reduce-top n keyfn cmp conj! (transient to) coll))
     (do          (reduce-top n keyfn cmp conj             to  coll)))))

(defn top
  "Returns a sorted vector of the top `n` items from `coll` using `reduce-top`."
  ([n           coll] (top-into [] n identity compare coll))
  ([n keyfn     coll] (top-into [] n keyfn    compare coll))
  ([n keyfn cmp coll] (top-into [] n keyfn    cmp     coll)))

(comment [(top 20 [2 3 5 3 88 nil]) (sort [2 3 5 3 88 nil])])

;;;; Date & time

(defn secs->ms ^long [secs] (* (long secs)  1000))
(defn ms->secs ^long [ms]   (quot (long ms) 1000))
(defn ms "Returns ~number of milliseconds in period defined by given args."
  [& {:as opts :keys [years months weeks days hours mins secs msecs ms]}]
  (have? #{:years :months :weeks :days :hours :mins :secs :msecs :ms}
    :in (keys opts))
  (round0
    (+
      (if years  (* (double years)  #=(* 1000 60 60 24 365))    0.0)
      (if months (* (double months) #=(* 1000 60 60 24 29.53))  0.0)
      (if weeks  (* (double weeks)  #=(* 1000 60 60 24 7))      0.0)
      (if days   (* (double days)   #=(* 1000 60 60 24))        0.0)
      (if hours  (* (double hours)  #=(* 1000 60 60))           0.0)
      (if mins   (* (double mins)   #=(* 1000 60))              0.0)
      (if secs   (* (double secs)   1000)                       0.0)
      (if msecs     (double msecs)                              0.0)
      (if ms        (double ms)                                 0.0))))

(def secs (comp ms->secs ms))
(comment #=(ms   :years 88 :months 3 :days 33)
         #=(secs :years 88 :months 3 :days 33))

(defmacro msecs "Compile-time version of `ms`" [& opts]
  (eval `(taoensso.encore/ms ~@opts)))

(comment (macroexpand '(msecs :weeks 3)))

#?(:clj
   (defn- -simple-date-format
     "Returns a SimpleDateFormat ThreadLocal proxy."
     [pattern locale timezone]
     (let [pattern
           (case pattern
             :iso8601 "yyyy-MM-dd'T'HH:mm:ss.SSSX"
             :rss2    "EEE, dd MMM yyyy HH:mm:ss z"
             pattern)

           locale
           (if (kw-identical? locale :jvm-default)
             nil ; (Locale/getDefault)
             locale)

           timezone
           (if (kw-identical? timezone :jvm-default)
             nil ; (TimeZone/getDefault)
             (if (kw-identical? timezone :utc)
               (TimeZone/getTimeZone "UTC")
               timezone))]

       (thread-local-proxy
         (let [^SimpleDateFormat sdf
               (if locale
                 (SimpleDateFormat. ^String pattern ^Locale locale)
                 (SimpleDateFormat. ^String pattern))]
           (when timezone (.setTimeZone sdf ^TimeZone timezone))
           sdf)))))

#?(:clj
   (defn simple-date-format*
     ^java.text.SimpleDateFormat [pattern locale timezone]
     (.get ^ThreadLocal (-simple-date-format pattern locale timezone))))

#?(:clj
   (defn simple-date-format "Returns a thread-local `java.text.SimpleDateFormat`."
     ^java.text.SimpleDateFormat [pattern & [{:keys [locale timezone] :as opts}]]
     (.get ^ThreadLocal (-simple-date-format pattern locale timezone))))

(comment (qb 1e5 (.format (simple-date-format "yyyy-MMM-dd") (Date.))))

;;;; Macro env

(defmacro get-env []
  (let [ks (reduce
             (fn [acc in]
               (if (str-starts-with? (name in) "__") ; Hide privates
                 acc ; Strip primitive tags which can cause issues:
                 (conj acc (without-meta in))))
             [] (keys &env))]
    `(zipmap '~ks ~ks)))

(comment [(let [x :x] (get-env)) ((fn [^long x] (get-env)) 0)])

;;;; IO

#?(:clj (defn  get-sys-val ([id] (get-sys-val  id id)) ([prop-id env-id] (or (System/getProperty prop-id) (System/getenv env-id)))))
#?(:clj (defn read-sys-val ([id] (read-sys-val id id)) ([prop-id env-id] (when-let [s (get-sys-val prop-id env-id)] (read-edn s)))))

#?(:clj
   (defn get-sys-bool
     "If `prop-id` JVM property or `env-id` environment variable are set:
       - Returns `true`  if set value is e/o #{\"1\" \"t\" \"true\" \"T\" \"TRUE\"}
       - Returns `false` if set value is e/o #{\"0\" \"f\" \"false\"\"F\" \"FALSE\"}
       - Otherwise throws

     Returns `default` if neither property nor environment variable is set."
     [default prop-id env-id]
     (if-let [sv (get-sys-val prop-id env-id)]
       (case  sv
         ("1" "t" "true"  "T" "TRUE")  true
         ("0" "f" "false" "F" "FALSE") false
         (throw
           (ex-info "Unexpected `get-sys-bool` value"
             {:value   sv
              :prop-id prop-id
              :env-id  env-id
              :default default})))

       default)))

#?(:clj
   (defn slurp-resource
     "Returns slurped named resource on classpath, or nil when resource not found."
     [rname]
     (when-let [r (io/resource rname)]
       (try
         (slurp (io/reader r))
         (catch Exception e
           (throw (ex-info "Failed to slurp resource" {:rname rname} e)))))))

#?(:clj
   (defn get-file-resource-?last-modified
     "Returns last-modified time for file backing given named resource, or nil
     if file doesn't exist."
     [rname]
     (when-let [file (try (->> rname io/resource io/file) (catch Exception _))]
       (.lastModified ^java.io.File file))))

#?(:clj
   (def file-resources-modified?
     "Returns true iff any files backing the given named resources have changed
     since last call."
     (let [udts_ (atom {}) ; {<rnames> <udt-or-udts>}
           swap! (fn [ks v] (swap-in! udts_ ks (fn [?v] (swapped v (when (not= v ?v) v)))))
           rnames->rgroup (fmemoize (fn [rnames] (into (sorted-set) rnames)))]
       (fn [rnames & [?id]]
         (let [rgroup (rnames->rgroup rnames)]
           (swap! [?id rgroup] (mapv get-file-resource-?last-modified rgroup)))))))

#?(:clj
   (def slurp-file-resource
     "Like `slurp-resource` but caches slurps against file's last-modified udt."
     (let [;; {<rname> [<content_> <last-modified-udt>]}
           cache_ (atom {})]
       (fn [rname]
         (let [curr-udt (or (get-file-resource-?last-modified rname) -1)]
           (force
             (swap-in! cache_ [rname]
               (fn [[?prev-content_ ?prev-udt :as ?v]]
                 (if (= curr-udt ?prev-udt)
                   (swapped ?v ?prev-content_)
                   (let [content_ (delay (slurp-resource rname))]
                     (swapped [content_ curr-udt] content_)))))))))))

(comment (slurp-file-resource "log4j.properties"))

#?(:clj
   (defn get-pom-version
     "Returns POM version string for given Maven dependency, or nil."
     [dep-sym]
     (let [path (clojure.core/format "META-INF/maven/%s/%s/pom.properties"
                  (or (namespace dep-sym)
                    (name      dep-sym))
                  (name dep-sym))]
       (when-let [props (io/resource path)]
         (with-open [stream (io/input-stream props)]
           (let [props (doto (java.util.Properties.) (.load stream))]
             (.getProperty props "version")))))))

(comment (get-pom-version 'com.taoensso/encore))

#?(:clj
   (defn get-hostname "Returns local hostname string, or nil."
     []
     (try (.getHostName (java.net.InetAddress/getLocalHost))
          (catch java.net.UnknownHostException _ nil))))

(comment (get-hostname))

;;;; Async

#?(:clj
   (defn future-pool
     "Returns a simple semaphore-limited wrapper of Clojure's standard `future`:
       (fn
         [f] - Blocks to acquire a future, then executes (f) on that future.
         [ ] - Blocks to acquire all futures, then immediately releases them.
               Useful for blocking till all outstanding work completes.
     Timeout variants are also provided."
     ;; TODO Actually use an independent pool, not urgent
     [n]
     (let [n    (long n)
           s    (java.util.concurrent.Semaphore. n)
           msecs java.util.concurrent.TimeUnit/MILLISECONDS
           fp-call
           (fn [f]
             (if (fn? f)
               (future (try (f) (finally (.release s))))
               (do
                 (.release s)
                 (throw (ex-info "Not a fn" {:given f :type (type f)})))))]

       (fn fp
         ([ ] (.acquire s n) (.release s n) true)
         ([f] (.acquire s) (fp-call f))

         ([^long timeout-ms timeout-val]
          (if (.tryAcquire s n timeout-ms msecs)
            (do (.release s n) true)
            timeout-val))

         ([^long timeout-ms timeout-val f]
          (if (.tryAcquire s timeout-ms msecs)
            (fp-call f)
            timeout-val))))))

(comment
  (time
    (let [fp (future-pool 2)]
      [(fp (fn [] (Thread/sleep 2000) (println "2000")))
       (fp (fn [] (Thread/sleep 500)  (println "500")))
       (fp 200 "timeout" (fn [] (Thread/sleep 900) (println "900")))
       (fp (fn [] (Thread/sleep 3000) (println "3000")))
       (fp)])))

;;;; Benchmarking

(defmacro time-ms "Returns number of milliseconds it took to execute body."
  [& body] `(let [t0# (now-udt*)] ~@body (- (now-udt*) t0#)))

(defmacro time-ns "Returns number of nanoseconds it took to execute body."
  [& body] `(let [t0# (now-nano*)] ~@body (- (now-nano*) t0#)))

(defmacro quick-bench "Returns fastest of 3 sets of times for each form, in msecs."
  ([nlaps form & more] (mapv (fn [form] `(quick-bench ~nlaps ~form)) (cons form more)))
  ([nlaps form]
   `(let [nlaps# ~nlaps
          ;; 3 warmup sets, 3 working sets:
          [nsets# nlaps#] (if (vector? nlaps#) nlaps# [6 nlaps#])
          [nsets# nlaps#] (have pos-num? nsets# nlaps#)]
      (round2
        (/ (double
             (reduce min
               (for [_# (range nsets#)]
                 (time-ns (dotimes [_# nlaps#] (do ~form))))))
          1e6)))))

(defmacro qb [& args] `(quick-bench ~@args)) ; Alias
(comment (qb [4 1e6] (first [:a]) (nth [:a] 0)))

#?(:clj
   (defn bench*
     "Repeatedly executes fn and returns time taken to complete execution."
     [nlaps {:keys [nlaps-warmup nthreads as-ns?]
             :or   {nlaps-warmup 0
                    nthreads     1}} f]
     (try
       (dotimes [_ nlaps-warmup] (f))
       (let [nanosecs
             (if (= nthreads 1)
               (time-ns (dotimes [_ nlaps] (f)))
               (let [nlaps-per-thread (/ nlaps nthreads)]
                 (time-ns
                   (let [futures (repeatedly-into [] nthreads
                                   (fn [] (future (dotimes [_ nlaps-per-thread] (f)))))]
                     (mapv deref futures)))))]
         (if as-ns? nanosecs (round0 (/ nanosecs 1e6))))
       (catch Throwable t
         (println (str "Bench failure: " (.getMessage t)))
         -1))))

(defmacro bench [nlaps opts & body] `(bench* ~nlaps ~opts (fn [] ~@body)))

;;;; Browser stuff

#?(:cljs
   (do ; Basic browser logging
     (def ^:private console-log
       (if-not (exists? js/console)
         (fn [& xs] nil)
         (fn [& xs] (when-let [f js/console.log]
                      (.apply f js/console (into-array xs))))))

     (def  log console-log) ; Raw args
     (defn logp [    & xs] (console-log (str-join " " (map nil->str) xs)))
     (defn sayp [    & xs] (js/alert    (str-join " " (map nil->str) xs)))
     (defn logf [fmt & xs] (console-log (format* fmt xs)))
     (defn sayf [fmt & xs] (js/alert    (format* fmt xs)))))

#?(:cljs
   (defn get-win-loc "Returns `js/window`'s current location as a map."
     []
     (when-let [js-win js-?win]
       (when-let [loc (.-location js-win)]
         {;; Ref. http://bl.ocks.org/abernier/3070589
          :href     (.-href     loc) ; "http://www.example.org:80/foo/bar?q=baz#bang"
          :protocol (.-protocol loc) ; "http:" ; Note the :
          :hostname (.-hostname loc) ; "example.org"
          :host     (.-host     loc) ; "example.org:80"
          :pathname (.-pathname loc) ; "/foo/bar"
          :search   (.-search   loc) ; "?q=baz"
          :hash     (.-hash     loc) ; "#bang"
          }))))

#?(:cljs
   (do
     (def ^:private xhr-pool_ (delay (goog.net.XhrIoPool.)))
     (defn- get-pooled-xhr!
       "Returns an immediately available XhrIo instance, or nil. The instance must
       be released back to pool manually."
       [] (let [result (.getObject @xhr-pool_)] (if (undefined? result) nil result)))

     (def ^:private js-form-data? (if (exists? js/FormData) (fn [x] (instance? js/FormData x)) (fn [x] nil)))
     (def ^:private js-file?      (if (exists? js/File)     (fn [x] (instance? js/File     x)) (fn [x] nil)))
     (def ^:private coerce-xhr-params "Returns [<uri> <?data>]"
       (let [url-encode
             (fn url-encode
               ([params]
                (when (seq params)
                  (-> params clj->js gquery-data/createFromMap .toString)))

               ([uri params]
                (let [qstr (url-encode params)
                      uri-with-query (if (str/blank? qstr) uri (str uri "?" qstr))]
                  [uri-with-query nil])))

             adaptive-encode
             (fn [uri params]
               (cond
                 (js-form-data? params) [uri params]
                 :do (have? map? params)

                 (and    (exists? js/FormData) (rsome js-file? (vals params)))
                 (let [form-data (js/FormData.)]
                   (doseq [[k v] params] (.append form-data (name k) v))
                   [uri form-data])

                 ;; Avoiding FormData as default since default Compojure
                 ;; middleware doesn't seem to keywordize FormData keys?
                 :else [uri (url-encode params)]))]

         (fn [uri method params]
           (have? [:or nil? map? js-form-data?] params)
           (case method
             :get  (url-encode      uri params)
             :post (adaptive-encode uri params)
             :put  (adaptive-encode uri params)))))))

#?(:cljs
   (defn ajax-lite
     "Alpha, subject to change. Simple, lightweight Ajax via Google Closure.
     Returns the resulting XhrIo[1] instance, or nil.

     (ajax-lite \"/my-post-route\"
       {:method     :post
        :params     {:username \"Rich Hickey\" :type \"Awesome\"}
        :headers    {\"Foo\" \"Bar\"}
        :resp-type  :text
        :timeout-ms 7000
        :with-credentials? false ; Enable if using CORS (requires xhr v2+)
       }
       (fn async-callback-fn [resp-map]
         (let [{:keys [success? ?status ?error ?content ?content-type]} resp-map]
           ;; ?status - e/o #{nil 200 404 ...}, non-nil iff server responded
           ;; ?error  - e/o #{nil <http-error-status-code> <exception> :timeout
                              :abort :http-error :exception :xhr-pool-depleted}
           (js/alert (str \"Ajax response: \" resp-map)))))

     [1] Ref. https://developers.google.com/closure/library/docs/xhrio"

     [uri {:keys [method params headers timeout-ms resp-type with-credentials?] :as opts
           :or   {method :get timeout-ms 10000 resp-type :auto}}
      callback-fn]

     (have? [:or nil? nat-int?] timeout-ms)

     (if-let [xhr (get-pooled-xhr!)]
       (catching
         (let [timeout-ms (or (:timeout opts) timeout-ms) ; Deprecated opt
               xhr-method (case method :get "GET" :post "POST" :put "PUT")

               [xhr-uri xhr-?data]
               (coerce-xhr-params uri method params)

               xhr-headers
               (let [headers (map-keys #(str/lower-case (name %)) headers)
                     headers (assoc-some headers "x-requested-with"
                               (get headers "x-requested-with" "XMLHTTPRequest"))]
                 ;; `x-www-form-urlencoded`/`multipart/form-data` content-type
                 ;; will be added by Closure if a custom content-type isn't provided
                 (clj->js headers))

               ?progress-listener
               (when-let [pf (:progress-fn opts)]
                 (.setProgressEventsEnabled xhr true)
                 (gevents/listen xhr goog.net.EventType/PROGRESS
                   (fn [ev]
                     (let [length-computable? (.-lengthComputable ev)
                           loaded (.-loaded ev)
                           total  (.-total  ev)
                           ?ratio (when (and length-computable? (not= total 0))
                                    (/ loaded total))]
                       (pf
                         {:?ratio ?ratio
                          :length-computable? length-computable?
                          :loaded loaded
                          :total  total
                          :ev     ev})))))]

           (doto xhr
             (gevents/listenOnce goog.net.EventType/READY
               (fn [_] (.releaseObject @xhr-pool_ xhr)))

             (gevents/listenOnce goog.net.EventType/COMPLETE
               (fn wrapped-callback-fn [resp]
                 (let [success? (.isSuccess xhr) ; true iff no error or timeout
                       -status  (.getStatus xhr) ; -1, 200, etc.

                       [?status ?content-type ?content]
                       (when (not= -status -1) ; Got a response from server
                         (let [;; Case insensitive get:
                               ?content-type (.getResponseHeader xhr "content-type")
                               ?content
                               (let [resp-type
                                     (cond
                                       (not= resp-type :auto) resp-type
                                       (nil? ?content-type)   :text
                                       :else
                                       (let [cts (str/lower-case (str ?content-type))
                                             match? (fn [s] (str-contains? cts s))]
                                         (cond
                                           (match? "/edn")     :edn
                                           (match? "/json")    :json
                                           (match? "/xml")     :xml
                                           ;; (match? "/html") :text
                                           :else               :text)))]

                                 (catching
                                   (case resp-type
                                     :edn  (read-edn (.getResponseText xhr))
                                     :json           (.getResponseJson xhr)
                                     :xml            (.getResponseXml  xhr)
                                     :text           (.getResponseText xhr))

                                   _e ; Undocumented, subject to change:
                                   {:ajax/bad-response-type resp-type
                                    :ajax/resp-as-text (.getResponseText xhr)}))]

                           [-status ?content-type ?content]))]

                   (when ?progress-listener
                     (gevents/unlistenByKey ?progress-listener))

                   (callback-fn
                     {:raw-resp      resp
                      :xhr           xhr ; = (.-target resp)
                      :success?      success?
                      :?status       ?status
                      :?content-type ?content-type
                      :?content      ?content
                      :?error
                      (if success?
                        nil
                        (cond
                          ?status ?status ; Http error status code (e.g. 404)
                          :else
                          (get {goog.net.ErrorCode/NO_ERROR   nil
                                goog.net.ErrorCode/EXCEPTION  :exception
                                goog.net.ErrorCode/HTTP_ERROR :http-error
                                goog.net.ErrorCode/ABORT      :abort
                                goog.net.ErrorCode/TIMEOUT    :timeout}
                            (.getLastErrorCode xhr)
                            :unknown)))})))))

           (.setTimeoutInterval xhr (or timeout-ms 0)) ; nil = 0 = no timeout
           (when with-credentials?
             (.setWithCredentials xhr true)) ; Requires xhr v2+

           (.send xhr xhr-uri xhr-method xhr-?data xhr-headers)
           xhr)

         e
         (do
           (.releaseObject @xhr-pool_ xhr)
           (callback-fn {:?error e})
           nil))

       (do ; Pool failed to return an available xhr instance
         (callback-fn {:?error :xhr-pool-depleted})
         nil))))

;;;; Ring

#?(:clj
   (defn session-swap
     "Small util to help correctly manage (modify) funtional sessions. Please use
     this when writing Ring middleware! It's *so* easy to get this wrong and end up
     with subtle, tough-to-diagnose issues."
     [rreq rresp f & args]
     (when rresp
       (let [base (get rresp :session (get rreq :session))
             new-session (if args (apply f base args) (f base))]
         (assoc rresp :session new-session)))))

#?(:clj
   (defn normalize-headers [rreq-or-rresp]
     (when rreq-or-rresp
       (assoc rreq-or-rresp :headers (map-keys str/lower-case (:headers rreq-or-rresp))))))

(comment (normalize-headers {:headers {"Foo1" "bar1" "FOO2" "bar2" "foo3" "bar3"}}))

#?(:clj
   (defn -ring-merge-headers
     "Experimental."
     [h1 h2]
     (reduce-kv
       (fn [m k2 v2]
         (if-let [e1 (find h1 k2)]
           (let [v1 (val e1)
                 v3
                 (if (vector? v1)
                   (if (vector? v2)
                     (if (:add (meta v2)) ; vec <- vec
                       (into v1 v2)
                       (do      v2))
                     (conj v1 v2))        ; vec <- el
                   (if (vector? v2)
                     (if (:add (meta v2)) ; el <- vec
                       (into [v1] v2)
                       (do        v2))
                     #_[v1 v2] v2))       ; el <- el
                 ]

             (assoc m k2 v3))
           (assoc   m k2 v2)))
       h1
       h2)))

(comment
  (-ring-merge-headers
    {"a" "A1" "b"        "B1"  "c" "C1"}
    {"a" "A2" "b" ^:add ["B2"] "d" "D2"}))

#?(:clj
   (do
     (defn ring-resp-map        [x] (when x (if (map? x) x {:body x})))
     (defn ring-set-body        [body    rresp] (assoc (ring-resp-map rresp) :body    body))
     (defn ring-set-status      [code    rresp] (assoc (ring-resp-map rresp) :status  code))
     (defn ring-set-headers     [headers rresp] (assoc (ring-resp-map rresp) :headers headers))
     (defn ring-default-headers [headers rresp] (assoc (ring-resp-map rresp) :headers (-ring-merge-headers headers (get rresp :headers))))
     (defn ring-merge-headers   [headers rresp] (assoc (ring-resp-map rresp) :headers (-ring-merge-headers (get rresp :headers) headers)))))

(comment
  (ring-merge-headers {"BAR" "baz"} {:body "foo"})
  (ring-merge-headers {"bar" "baz"} "foo"        )
  (ring-merge-headers {"bar" ^:add ["baz2"]} {:body "foo" :headers {"bar" "baz1"}}))

#?(:clj
   (defn ring-redirect-resp
     ([     url      ] (ring-redirect-resp :temp url nil))
     ([kind url      ] (ring-redirect-resp kind  url nil))
     ([kind url flash]
      {:headers {"location" url}
       :body    nil
       :flash   flash
       :status
       (case kind
         (301 :permanent :perm)     301
         (302 :temporary :temp nil) 302
         kind)})))

(comment (ring-redirect-resp 303 "/foo" "boo!"))

(defn url-encode "Based on https://goo.gl/fBqy6e"
  #?(:clj  [s & [encoding]] :cljs [s])
  (when s
    #?(:clj  (-> (str s)
               (java.net.URLEncoder/encode (str (or encoding "UTF-8")))
               (str/replace "*" "%2A") ; Cautious, https://stackoverflow.com/a/25149577/1982742
               (str/replace "+" "%20") ; Cautious, https://stackoverflow.com/a/40292770/1982742
               )
       :cljs (-> (str s)
               (js/encodeURIComponent s)
               (str/replace "*" "%2A")))))

(defn url-decode "Stolen from http://goo.gl/99NSR1"
  [s & [encoding]]
  (when s
    #?(:clj  (java.net.URLDecoder/decode (str s) (str (or encoding "UTF-8")))
       :cljs (js/decodeURIComponent      (str s)))))

(comment
  (url-decode (url-encode "Hello there"))
  (url-decode "hello+there"))

(defn format-query-string [m]
  (let [param (fn [k v]  (str (url-encode (as-qname k)) "="
                              (url-encode (or (as-?qname v) (str v)))))
        join  (fn [strs] (str/join "&" strs))]
    (if (empty? m)
      ""
      (join
        (for [[k v] m :when (some? v)]
          (if (sequential? v)
            (join (mapv (partial param k) (or (seq v) [""])))
            (param k v)))))))

(comment
  (format-query-string {})
  (format-query-string {:k1 "v1" :k2 "v2" :k3 nil :k4 "" :k5 ["v4a" "v4b" 7] :k6 []})
  (format-query-string {:a/b :c/d})
  (format-query-string {:k nil}) ; Nb to allow removing pre-existing params, etc.
  )

(defn- assoc-conj [m k v]
  (assoc m k (if-let [cur (get m k)] (if (vector? cur) (conj cur v) [cur v]) v)))

(comment (assoc-conj {:a "a"} :a "b"))

(defn parse-query-params "Based on `ring-codec/form-decode`."
  [s & [keywordize? encoding]]
  (if (or (str/blank? s) (not (str-contains? s "=")))
    {}
    (let [;; For convenience (e.g. JavaScript win-loc :search)
          s (if (str-starts-with? s "?") (subs s 1) s)
          m (reduce
              (fn [m param]
                (if-let [[k v] (str/split param #"=" 2)]
                  (assoc-conj m (url-decode k encoding) (url-decode v encoding))
                  m))
              {}
              (str/split s #"&"))]
      (if-not keywordize?
        m
        (map-keys keyword m)))))

(comment
  (parse-query-params nil)
  (parse-query-params "?foo=bar" :keywordize)
  (-> {:k1 "v1" :k2 "v2" :k3 nil :k4 "" :k5 ["v4a" "v4b"] :k6 [] :k7 47}
      (format-query-string)
      (parse-query-params)))

(defn merge-url-with-query-string [url m]
  (let [[url ?qstr] (str/split (str url) #"\?" 2)
        qmap  (merge
                (when ?qstr (map-keys keyword (parse-query-params ?qstr)))
                (map-keys keyword m))
        ?qstr (as-?nblank (format-query-string qmap))]
    (if-let [qstr ?qstr] (str url "?" qstr) url)))

(comment
  (merge-url-with-query-string "/" nil)
  (merge-url-with-query-string "/?foo=bar" nil)
  (merge-url-with-query-string "/?foo=bar" {"foo" "overwrite"})
  (merge-url-with-query-string "/?foo=bar" {:foo  "overwrite"})
  (merge-url-with-query-string "/?foo=bar" {:foo  nil})
  (merge-url-with-query-string "/?foo=bar" {:foo2 "bar2" :num 5 :foo nil}))

;;;; Stubs

(do
  #?(:cljs (defn -new-stubfn_ [name] (volatile! (fn [& args]  (throw (ex-info (str "Attempting to call uninitialized stub fn (" name ")") {:stub name :args args}))))))
  #?(:cljs (defn -assert-unstub-val [f] (if (fn?     f) f (throw (ex-info "Unstub value must be a fn"     {:given f :type (type f)}))))
     :clj  (defn -assert-unstub-val [s] (if (symbol? s) s (throw (ex-info "Unstub value must be a symbol" {:given s :type (type s)})))))
  #?(:clj
     (defmacro -intern-stub [ns stub-sym stub-var src]
       (-assert-unstub-val src)
       `(let [src-var# (var ~src)
              dst-var# ~stub-var
              dst-meta#
              (merge
                (dissoc      (meta dst-var#) :declared :redef)
                (select-keys (meta src-var#) [:arglists :doc]))]
          (intern '~ns (with-meta '~stub-sym dst-meta#)
            (.getRawRoot src-var#))))))

#?(:clj
   (defmacro defstub
     "Experimental. Declares a stub var that can be initialized from any
     namespace with `unstub-<stub-name>`. Decouples a var's declaration
     (location) and its initialization (value). Handy for defining vars in a
     shared ns from elsewhere (e.g. a private or cyclic ns)."
     [sym]
     (let [   stub-sym  sym
            unstub-sym (symbol (str  "unstub-" (name stub-sym)))
           -unstub-sym (symbol (str "-unstub-" (name stub-sym)))]
       `(if-cljs ; No declare/intern support
            (let [~'stubfn_ (-new-stubfn_ ~(name stub-sym))]
              (defn ~-unstub-sym [~'f]        (vreset! ~'stubfn_ (-assert-unstub-val ~'f)))
              (defn  ~unstub-sym [~'f]        (~-unstub-sym ~'f))
              (defn    ~stub-sym [~'& ~'args] (apply      @~'stubfn_ ~'args)))
          (let [stub-var# (declare ~(with-meta stub-sym {:redef true}))]
            (defmacro ~(with-meta unstub-sym {:doc "Initializes stub"})
              [~'x] ; ~'sym for clj, ~'f for cljs
              `(if-cljs
                   ;; In Cljs, a macro+fn can have the same name. Preference will be
                   ;; given to the macro in contexts where both are applicable.
                   ;; So there's 3 cases to consider:
                   ;;   1. clj   stub: def var, clj macro
                   ;;   2. cljs  stub: def volatile, 2 fns
                   ;;   3. clj/s stub: def volatile, 2 fns, var, and clj/s macro
                    (~'~(symbol (str *ns*) (str (name -unstub-sym))) ~~'x)
                 (-intern-stub ~'~(symbol (str *ns*)) ~'~stub-sym
                   ~stub-var# ~~'x))))))))

(comment
  (defn- -foo ^long [y] (* y y))
  (macroexpand-all '(defstub foo))
  (defstub foo)
  (unstub-foo -foo)
  (qb 1e6 (-foo 5) (foo 5)) ; [68.49 71.88]
  (meta (first (:arglists (meta #'foo))))

  (do
    #?(:cljs (def cljs-thing "cljs-thing")
       :clj  (def clj-thing  "clj-thing"))

    (defmacro cljs-macro [] `(if-cljs cljs-thing clj-thing))

    #?(:clj  (cljs-macro)
       :cljs (enc-macros/cljs-macro))

    #?(:cljs (enc-macros/defstub stub-test)
       :clj             (defstub stub-test))

    #?(:cljs (enc-macros/unstub-stub-test identity)
       :clj             (unstub-stub-test identity))))

;;;; ns filter

(let [always (fn always [?in-str] true)
      never  (fn never  [?in-str] false)

      wild-str->?re-pattern
      (fn [s]
        (when (str-contains? s "*")
          (re-pattern
            (-> (str "^" s "$")
              (str/replace "." "\\.")
              (str/replace "*" "(.*)")))))

      compile
      (fn compile [spec cache?] ; Returns (fn match? [in-str])
        (cond
          (#{:any "*"    } spec) always
          (#{:none #{} []} spec) never
          (re-pattern?     spec) (fn [in-str] (re-find spec in-str))
          (string?         spec)
          (cond
            ;; Ambiguous: "," meant as splitter or literal? Prefer coll.
            ;; (str-contains? spec ",") (recur (mapv str/trim (str/split spec #",")) cache?)
            :if-let [re-pattern (wild-str->?re-pattern spec)]

            (recur re-pattern cache?)
            :else (fn [in-str] (= in-str spec)))

          (or (vector? spec) (set? spec))
          (cond
            ;; (empty? spec)   never
            ((set spec) "*")   always
            (= (count spec) 1) (recur (first spec) cache?)
            :else
            (let [[fixed-strs re-patterns]
                  (reduce
                    (fn [[fixed-strs re-patterns] spec]
                      (if-let [re-pattern (if (re-pattern? spec) spec (wild-str->?re-pattern spec))]
                        [      fixed-strs       (conj re-patterns re-pattern)]
                        [(conj fixed-strs spec)       re-patterns            ]))
                    [#{} []]
                    spec)

                  fx-match (not-empty fixed-strs) ; #{"foo" "bar"}, etc.
                  re-match
                  (when-let [re-patterns (not-empty re-patterns)] ; ["foo.*", "bar.*"], etc.
                    (let [f (fn [in-str] (rsome #(re-find % in-str) re-patterns))]
                      (if cache? (fmemoize f) f)))]

              (cond!
                (and fx-match re-match) (fn [in-str] (or (fx-match in-str) (re-match in-str)))
                fx-match fx-match
                re-match re-match)))

          :else
          (throw
            (ex-info "Unexpected compile spec type"
              {:given spec :type (type spec)}))))]

  (defn compile-str-filter
    "Compiles given spec and returns a fast (fn conform? [?in-str]).

    Spec may be:
      - A regex pattern. Will conform on match.
      - A string, in which any \"*\"s will act as wildcards (#\".*\").
        Will conform on match.

      - A vector or set of regex patterns or strings.
        Will conform on ANY match.
        If you need literal \"*\"s, use an explicit regex pattern instead.

      - {:allow <allow-spec> :deny <deny-spec> :cache? <bool>}.
        Will conform iff allow-spec matches AND deny-spec does NOT.

    Input may be: namespace strings, class names, etc.
    Useful as string allowlist (whitelist) and/or denylist (blacklist).

    Spec examples:
      #{}, \"*\", \"foo.bar\", \"foo.bar.*\", #{\"foo\" \"bar.*\"},
      {:allow #{\"foo\" \"bar.*\"} :deny #{\"foo.*.bar.*\"}}"

    [spec]
    (if-not (map? spec)
      (recur {:allow spec :deny nil})
      (let [cache?         (get spec :cache?)
            allow-spec (or (get spec :allow) (get spec :whitelist))
            deny-spec  (or (get spec :deny)  (get spec :blacklist))

            allow (when-let [as allow-spec] (compile as cache?))
            deny  (when-let [ds deny-spec]  (compile ds cache?))]

        (cond
          (= deny  always) never
          (= allow never)  never

          (and allow deny)
          (fn [?in-str]
            (let [in-str (str ?in-str)]
              (if (allow in-str)
                (if (deny in-str)
                  false
                  true)
                false)))

          allow (if (= allow always) always (fn [?in-str] (if (allow (str ?in-str)) true false)))
          deny  (if (= deny  never)  always (fn [?in-str] (if (deny  (str ?in-str)) true false)))
          :else
          (throw
            (ex-info "compile-str-filter: `allow-spec` and `deny-spec` cannot both be nil"
              {:allow-spec allow-spec :deny-spec deny-spec})))))))

(comment
  (def sf? (compile-str-filter #{"foo.*" "bar"}))
  (qb 1e5 (sf? "foo")) ; 26

  (-> "foo" ((compile-str-filter nil)))           :ex
  (-> "foo" ((compile-str-filter :any)))          true
  (-> "foo" ((compile-str-filter #{"foo*"})))     true
  (-> "foo" ((compile-str-filter ["bar" "foo"]))) true
  (-> "foo" ((compile-str-filter ["bar" "f*"])))  true
  (-> "foo" ((compile-str-filter {:allow :any :deny :any}))) false
  (-> "foo" ((compile-str-filter {:allow "foo*"}))) true)

;;;; Scheduling
;; Considered also adding `call-at-interval` but decided against it since the
;; API we'd want for that would be less interesting and more impl specific;
;; i.e. the cost/benefit would be poor.

(do
  (defprotocol   ITimeoutImpl (-schedule-timeout [_ msecs f]))
  (deftype DefaultTimeoutImpl [#?(:clj ^java.util.Timer timer)]
                 ITimeoutImpl
    (-schedule-timeout [_ msecs f]
      #?(:cljs (.setTimeout js/window f msecs)
         :clj
         (let [tt (proxy [java.util.TimerTask] []
                    (run [] (catching (f))))]
           (.schedule timer tt (long msecs))))))

  (defonce default-timeout-impl_
    "Simple one-timeout timeout implementation provided by platform timer.
    O(logn) add, O(1) cancel, O(1) tick. Fns must be non-blocking or cheap.
    Similar efficiency to core.async timers (binary heap vs DelayQueue)."
    (delay
      (DefaultTimeoutImpl.
        #?(:clj (java.util.Timer. "encore/timer" true)))))

  (def ^:private -tout-pending   (new-object))
  (def ^:private -tout-cancelled (new-object))
  (defn- tout-result [result_]
    (if (kw-identical? result_ -tout-pending)
      :timeout/pending
      (if (kw-identical? result_ -tout-cancelled)
        :timeout/cancelled
        @result_))))

(defprotocol ITimeoutFuture
  (tf-state      [_] "Returns a map of timeout's public state.")
  (tf-poll       [_] "Returns :timeout/pending, :timeout/cancelled, or the timeout's completed result.")
  (tf-done?      [_] "Returns true iff the timeout is not pending (i.e. has a completed result or is cancelled).")
  (tf-pending?   [_] "Returns true iff the timeout is pending.")
  (tf-cancelled? [_] "Returns true iff the timeout is cancelled.")
  (tf-cancel!    [_] "Returns true iff the timeout was successfully cancelled (i.e. was previously pending)."))

#?(:cljs
   (deftype TimeoutFuture [f result__ udt]
     ITimeoutFuture
     (tf-state      [_] {:fn f :udt udt})
     (tf-poll       [_] (tout-result @result__))
     (tf-done?      [_] (not (kw-identical? @result__ -tout-pending)))
     (tf-pending?   [_]      (kw-identical? @result__ -tout-pending))
     (tf-cancelled? [_]      (kw-identical? @result__ -tout-cancelled))
     (tf-cancel!    [_] (compare-and-set! result__ -tout-pending -tout-cancelled))

     IPending (-realized?  [t] (tf-done? t))
     IDeref   (-deref      [t] (tf-poll  t))))

#?(:clj
   (deftype TimeoutFuture
     [f result__ ^long udt ^java.util.concurrent.CountDownLatch latch]
     ITimeoutFuture
     (tf-state      [_] {:fn f :udt udt})
     (tf-poll       [_] (tout-result @result__))
     (tf-done?      [_] (not (kw-identical? @result__ -tout-pending)))
     (tf-pending?   [_]      (kw-identical? @result__ -tout-pending))
     (tf-cancelled? [_]      (kw-identical? @result__ -tout-cancelled))
     (tf-cancel!    [_]
       (if (compare-and-set! result__ -tout-pending -tout-cancelled)
         (do (.countDown latch) true)
         false))

     clojure.lang.IPending (isRealized  [t] (tf-done? t))
     clojure.lang.IDeref   (deref       [_] (.await latch) (tout-result @result__))
     clojure.lang.IBlockingDeref
     (deref [_ timeout-ms timeout-val]
       (if (.await latch timeout-ms java.util.concurrent.TimeUnit/MILLISECONDS)
         (tout-result @result__)
         timeout-val))

     java.util.concurrent.Future
     (isCancelled [t]   (tf-cancelled? t))
     (isDone      [t]   (tf-done?      t))
     (cancel      [t _] (tf-cancel!    t))))

#?(:clj  (defn          timeout-future? [x] (instance? TimeoutFuture x))
   :cljs (defn ^boolean timeout-future? [x] (instance? TimeoutFuture x)))

(defn call-after-timeout
  "Alpha, subject to change.
  Returns a TimeoutFuture that will execute `f` after given msecs.

  Does NOT do any automatic binding conveyance.

  Performance depends on the provided timer implementation (`impl_`).
  The default implementation offers O(logn) add, O(1) cancel, O(1) tick.

  See `ITimeoutImpl` for extending to arbitrary timer implementations."

  ;; Why no auto binding convyance? Explicit manual conveyance plays better
  ;; with cljs, and means less surprise with `future-fn`.
  ([      msecs f] (call-after-timeout default-timeout-impl_ msecs f))
  ([impl_ msecs f]
   (let [msecs (long msecs)
         udt   (+ (now-udt*) msecs) ; Approx instant to run
         result__ (atom -tout-pending)
         #?(:clj latch) #?(:clj (java.util.concurrent.CountDownLatch. 1))
         cas-f
         (fn []
           (let [result_ (delay (f))]
             (when (compare-and-set! result__ -tout-pending result_)
               @result_
               #?(:clj (.countDown latch)))))]

     (let [impl (force impl_)]
       (-schedule-timeout impl msecs cas-f))

     (TimeoutFuture. f result__ udt #?(:clj latch)))))

(defmacro after-timeout
  "Alpha, subject to change.
  Returns a TimeoutFuture that will execute body after timeout.
  Body must be non-blocking or cheap."
  [msecs & body] `(call-after-timeout ~msecs (fn [] ~@body)))

(comment
  @(after-timeout 500 (println "foo") "bar")
  (def ^:dynamic *foo* nil)
  (binding [*foo* "bar"] ; Note no auto conveyance
    ((:fn (tf-state (after-timeout 200 (println *foo*) *foo*))))))

;;;; Tests


(defn- -ex-message ; `ex-message` was only introduced in Clojure 1.10+
  [ex]
  #?(:clj  (when (instance? Throwable ex) (.getMessage ^Throwable ex))
     :cljs (when (instance? js/Error  ex) (.-message              ex))))

(defn -matching-throwable
  ([  ex] (when ex ex))
  ([c ex]
   (when
       (instance?
         (case c
           :default #?(:clj Exception :cljs js/Error)
           :any     #?(:clj Throwable :cljs js/Error)
           c)
         ex)
     ex))

  ([c pattern ex]
   (when
       (and
         (-matching-throwable c ex)
         (if (map? pattern)
           (if-let [data (ex-data ex)]
             (= pattern (select-keys data (keys pattern)))
             false)

           (boolean (re-find (re-pattern pattern) (-ex-message ex)))))
     ex)))

(comment
  (-matching-throwable                            (catching (/ 4 0) t t))
  (-matching-throwable :default #"Divide by zero" (catching (/ 4 0) t t))
  (-matching-throwable :default #"Nope"           (catching (/ 4 0) t t))
  (-matching-throwable :default #"Test"           (ex-info "Test" {:a :b}))
  (-matching-throwable :default {:a :b}           (ex-info "Test" {:a :b :c :d})))

(defmacro thrown
  "Evaluates `form` and returns ?throwable thrown by form that matches
  given criteria:

    - `c` may be:
      - A class (e.g. ArithmeticException, AssertionError, etc.)
      - `:default` => default platform throwable (Exception or js/Error)
      - `:any`     => any     platform throwable (Throwable or js/Error)

    - `pattern` may be
      - A string or Regex against which `ex-message` will be matched.
      - A map             against which `ex-data`    will be matched.

  Useful for unit tests, e.g.:
    (is (thrown :default {:a :b} (throw (ex-info \"Test\" {:a :b :c :d}))))"

  ([          form] `(-matching-throwable             (catching ~form ~'t ~'t)))
  ([c         form] `(-matching-throwable ~c          (catching ~form ~'t ~'t)))
  ([c pattern form] `(-matching-throwable ~c ~pattern (catching ~form ~'t ~'t))))

(comment
  (thrown                            (/ 4 0))
  (thrown :default #"Divide by zero" (/ 4 0))
  (thrown :default #"Nope"           (/ 4 0))
  (thrown :default #"Test" (throw (ex-info "Test" {:a :b})))
  (thrown :default {:a :b} (throw (ex-info "Test" {:a :b :c :d}))))

;;;; DEPRECATED

#?(:clj
   (defmacro deprecated
     "Elides body when `taoensso.elide-deprecated` JVM property or
     `TAOENSSO_ELIDE_DEPRECATED` environment variable is e/o #{\"true\" \"TRUE\"}."
     [& body]
     (if (get-sys-bool false
           "taoensso.elide-deprecated"
           "TAOENSSO_ELIDE_DEPRECATED")
       nil ; Elide
       `(do ~@body))))

(deprecated
  #?(:cljs (def get-window-location get-win-loc))
  #?(:clj  (def srng                secure-rng))
  (def backport-run!   run!)
  (def fq-name         as-qname)
  (def qname           as-qname)
  (def merge-deep-with nested-merge-with)
  (def merge-deep      nested-merge)
  (def parse-bool      as-?bool)
  (def parse-int       as-?int)
  (def parse-float     as-?float)
  (def swapped*        swapped)
  (def memoize-a0_     memoize_)
  (def memoize-a1_     memoize_)
  (def a0-memoize_     memoize_)
  (def a1-memoize_     memoize_)
  (def memoize-1       memoize-last)
  (def memoize1        memoize-last)
  (def memoize*        memoize)
  (def nnil?           some?)
  (def nneg-num?       nat-num?)
  (def nneg-int?       nat-int?)
  (def nneg-float?     nat-float?)
  (def uint?           nat-int?)
  (def pint?           pos-int?)
  (def nnil=           some=)
  (def as-?uint        as-?nat-int)
  (def as-?pint        as-?pos-int)
  (def as-?ufloat      as-?nat-float)
  (def as-?pfloat      as-?pos-float)
  (def as-uint         as-nat-int)
  (def as-pint         as-pos-int)
  (def as-ufloat       as-nat-float)
  (def as-pfloat       as-pos-float)
  (def run!*           run!)
  (def every           revery)
  (def ?subvec<idx     (comp not-empty      get-subvec))
  (def ?subvec<len     (comp not-empty      get-subvector))
  (def ?substr<idx     (comp as-?nempty-str get-substr))
  (def ?substr<len     (comp as-?nempty-str get-substring))
  (def dswap!          swap-in!*)
  (def nano-time       now-nano)
  (def swap!*          swap-in!*)
  (def -swap-cache!    -swap-val!)
  (def -unswapped      swapped-vec)
  (def -vswapped       swapped-vec)
  (def -swap-k!        -swap-val!)
  (def update-in*      update-in)
  (def idx-fn          counter)
  (def vec*            ensure-vec)
  (def set*            ensure-set)
  (def have-transducers? true)

  (def     pval?    pnum?)
  (def as-?pval as-?pnum)
  (def  as-pval  as-pnum)

  ;; Used by old versions of Timbre, Tufte
  (let [nolist? #(contains? #{nil [] #{}} %)]

    (defn compile-ns-filter
      "Deprecated, prefer `compile-str-filter` instead."
      ([ns-pattern         ] (compile-ns-filter ns-pattern nil))
      ([whitelist blacklist]

       (if (and (nolist? whitelist) (nolist? blacklist))
         (fn [_] true) ; Unfortunate API choice
         (compile-str-filter {:allow whitelist :deny blacklist})))))

  #?(:clj (defn set-body      [rresp body]    (ring-set-body      body    rresp)))
  #?(:clj (defn set-status    [rresp code]    (ring-set-status    code    rresp)))
  #?(:clj (defn merge-headers [rresp headers] (ring-merge-headers headers rresp)))
  #?(:clj (def  redirect-resp ring-redirect-resp))

  (defmacro if-lets       [& args]  `(taoensso.encore/if-let        ~@args))
  (defmacro when-lets     [& args]  `(taoensso.encore/when-let      ~@args))
  (defmacro if-not*       [& args]  `(taoensso.encore/if-not        ~@args))
  (defmacro cond*         [& args]  `(taoensso.encore/cond          ~@args))
  (defmacro defonce*      [& args]  `(taoensso.encore/defonce       ~@args))
  (defmacro have-in       [a1 & an] `(taoensso.encore/have  ~a1 :in ~@an))
  (defmacro have-in!      [a1 & an] `(taoensso.encore/have! ~a1 :in ~@an))
  (defmacro cond-throw    [& args]  `(taoensso.encore/cond!         ~@args))
  (defmacro catch-errors* [& args]  `(taoensso.encore/catching      ~@args))
  (defmacro use-fixtures* [& args]  `(taoensso.encore/use-fixtures  ~@args))
  (defmacro nano-time*    [& args]  `(taoensso.encore/now-nano*     ~@args))
  (defmacro qbench        [& args]  `(taoensso.encore/quick-bench   ~@args))
  (defmacro catch-errors  [& body]
    `(catching [(do ~@body) nil] e# [nil e#]))

 (defmacro -vol!       [val]           `(volatile!     ~val))
 (defmacro -vol-reset! [vol_ val]      `(vreset! ~vol_ ~val))
 (defmacro -vol-swap!  [vol_ f & args] `(vswap!  ~vol_ ~f ~@args))

  ;;; Prefer `str-join` when possible (needs Clojure 1.7+)
  #?(:cljs (defn undefined->nil [x] (if (undefined? x) nil x)))
  (defn spaced-str-with-nils [xs] (str/join " " (mapv nil->str xs)))
  (defn spaced-str [xs] (str/join " " #?(:clj xs :cljs (mapv undefined->nil xs))))

  ;; Arg order changed for easier partials, etc.:
  (defn round [n & [type nplaces]] (round* (or type :round) nplaces n))
  (defn approx=
    ([x y      ] (approx==       x y))
    ([x y signf] (approx== signf x y)))

  ;; & coll changed to coll:
  (defn join-once [sep & coll] (str-join-once sep coll))

  ;; Used by Carmine <= v2.7.0
  (defmacro repeatedly* [n & body] `(repeatedly-into* [] ~n ~@body))
  (defmacro repeatedly-into* "Deprecated" ; Used by Nippy < v2.10
    [coll n & body] `(repeatedly-into ~coll ~n (fn [] ~@body)))

  (defn nnil-set [x] (disj (ensure-set x) nil))

  ;;; Arg order changed for easier partials
  (defn keys=      [m ks] (ks=      ks m))
  (defn keys<=     [m ks] (ks<=     ks m))
  (defn keys>=     [m ks] (ks>=     ks m))
  (defn keys=nnil? [m ks] (ks-nnil? ks m))

  (defn rate-limiter* "Deprecated, prefer `limiter`" [specs]
    (let [ids? (rsome (fn [[_ _ id]] id) specs)
          lfn  (limiter specs)]
      (fn [& args]
        (when-let [[worst-sid backoff-ms] (apply lfn args)]
          (if ids?
            [backoff-ms worst-sid]
             backoff-ms)))))

  (defn rate-limit [specs f]
    (let [rl (rate-limiter* specs)]
      (fn [& args]
        (if-let [backoff (rl)]
          [nil backoff]
          [(f) nil]))))

  ;; API changed for greater flexibility:
  (defn rate-limiter [ncalls-limit window-ms] (rate-limiter* [[ncalls-limit window-ms]]))
  (defn rate-limited [ncalls-limit window-ms f]
    (let [rl (rate-limiter* [[ncalls-limit window-ms]])]
      (fn [& args]
        (if-let [backoff-ms (rl)]
          {:backoff-ms backoff-ms}
          {:result     (f)}))))

  ;; Used by Sente <= v1.4.0-alpha2
  (def logging-level (atom :debug)) ; Just ignoring this now

  #?(:cljs ; Used by Sente <= v1.1.0
     (defn set-exp-backoff-timeout! [nullary-f & [nattempt]]
       (when-let [js-win js-?win]
         (.setTimeout js-win nullary-f (exp-backoff (or nattempt 0))))))

  #?(:cljs
     (do ; Level-based Cljs logging (prefer Timbre v4+)
       (defonce ^:dynamic *log-level* "DEPRECATED" :debug)
       (def ^:private log?
         (let [->n {:trace 1 :debug 2 :info 3 :warn 4 :error 5 :fatal 6 :report 7}]
           (fn [level] (>= (->n level) (->n *log-level*)))))

       (defn tracef  [fmt & xs] (when (log? :trace)  (apply logf fmt xs)))
       (defn debugf  [fmt & xs] (when (log? :debug)  (apply logf fmt xs)))
       (defn infof   [fmt & xs] (when (log? :info)   (apply logf fmt xs)))
       (defn warnf   [fmt & xs] (when (log? :warn)   (apply logf (str "WARN: "  fmt) xs)))
       (defn errorf  [fmt & xs] (when (log? :error)  (apply logf (str "ERROR: " fmt) xs)))
       (defn fatalf  [fmt & xs] (when (log? :fatal)  (apply logf (str "FATAL: " fmt) xs)))
       (defn reportf [fmt & xs] (when (log? :report) (apply logf fmt xs)))))

  (defn greatest [coll & [?comparator]]
    (let [comparator (or ?comparator rcompare)]
      (reduce #(if (pos? (comparator %1 %2)) %2 %1) coll)))

  (defn least [coll & [?comparator]]
    (let [comparator (or ?comparator rcompare)]
      (reduce #(if (neg? (comparator %1 %2)) %2 %1) coll)))

  (defn clj1098 "Ref. http://goo.gl/0GzRuz" [x] (or x {}))

  (defn distinct-by "Deprecated, prefer `xdistinct`"
    [keyfn coll]
    (let [step (fn step [xs seen]
                 (lazy-seq
                   ((fn [[v :as xs] seen]
                      (when-let [s (seq xs)]
                        (let [v* (keyfn v)]
                          (if (contains? seen v*)
                            (recur (rest s) seen)
                            (cons v (step (rest s) (conj seen v*)))))))
                    xs seen)))]
      (step coll #{})))

  (defn distinctv "Deprecated, prefer `xdistinct`"
    ([      coll] (distinctv identity coll))
    ([keyfn coll]
     (let [tr (reduce (fn [[v seen] in]
                        (let [in* (keyfn in)]
                          (if-not (contains? seen in*)
                            [(conj! v in) (conj seen in*)]
                            [v seen])))
                [(transient []) #{}]
                coll)]
       (persistent! (nth tr 0)))))

  (defn map-kvs "Deprecated, prefer `reduce-kv`" [kf vf m]
    (if-not m {}
      (let [vf (cond (nil? vf) (fn [_ v] v) :else vf)
            kf (cond (nil? kf) (fn [k _] k)
                 (kw-identical? kf :keywordize) (fn [k _] (keyword k))
                 :else kf)]
        (persistent!
          (reduce-kv (fn [m k v] (assoc! m (kf k v) (vf k v)))
            (transient {}) m)))))

  (defn as-map "Deprecated, prefer `reduce-kvs`" [kvs & [kf vf]]
    (if (empty? kvs) {}
        (let [vf (cond (nil? vf) (fn [_ v] v) :else vf)
              kf (cond (nil? kf) (fn [k _] k)
                   (kw-identical? kf :keywordize) (fn [k _] (keyword k))
                   :else kf)]
          (persistent!
            (reduce-kvs
              (fn [m k v] (assoc! m (kf k v) (vf k v))) (transient {}) kvs)))))

  (defn keywordize-map [m] (map-keys keyword m))
  (defn removev [pred coll] (filterv (complement pred) coll))
  (defn nvec? [n x] (and (vector? x) (= (count x) n)))

  (defn memoized [cache f & args]
    (if-not cache ; {<args> <delay-val>}
      (apply f args)
      @(-swap-val! cache args (fn [?dv] (if ?dv ?dv (delay (apply f args)))))))

  (defn- translate-signed-idx [^long signed-idx ^long max-idx]
    (if (>= signed-idx 0)
      (min      signed-idx max-idx)
      (max 0 (+ signed-idx max-idx))))

  (comment (translate-signed-idx -3 5))

  (defn sub-indexes [x start-idx & {:keys [^long max-len ^long end-idx]}]
    (let [start-idx  ^long start-idx
          xlen       (count x) ; also = max-exclusive-end-idx
          ^long start-idx* (translate-signed-idx start-idx xlen)
          end-idx*   (long
                       (cond
                         max-len (min* (+ start-idx* max-len) xlen)
                         end-idx (inc ; Want exclusive
                                   ^long (translate-signed-idx end-idx xlen))
                         :else   xlen))]
      (if (> start-idx* end-idx*)
        ;; [end-idx* start-idx*] ; Allow wrapping
        [0 0] ; Disallow wrapping
        [start-idx* end-idx*])))

  (defn substr "Deprecated, prefer `get-substr` or `get-substring`"
    [s start-idx & [?max-len]]
    (let [[start-idx* end-idx*] (sub-indexes s start-idx :max-len ?max-len)]
      #?(:clj  (.substring ^String s start-idx* end-idx*)
         :cljs (.substring         s start-idx* end-idx*))))

  (comment (substr "hello" -1 1))

  (defn subvec* "Deprecated, prefer `get-subvec` or `get-subvector`"
    [v start-idx & [?max-len]]
    (let [[start-idx* end-idx*] (sub-indexes v start-idx :max-len ?max-len)]
      (subvec v start-idx* end-idx*)))

  (def  sentinel (new-object))
  (defn sentinel?     [x] (identical? x sentinel))
  (defn nil->sentinel [x] (if (nil? x) sentinel x))
  (defn sentinel->nil [x] (if (sentinel? x) nil x))

  (defn   singleton? [coll] (if (counted? coll) (= (count coll) 1) (not (next coll))))
  (defn ->?singleton [coll] (when (singleton? coll) (let [[c1] coll] c1)))
  (defn ->vec [x] (cond (vector? x) x (sequential? x) (vec x) :else [x]))

  (defn fzipmap [ks vs]
    (loop [m  (transient {})
           ks (seq ks)
           vs (seq vs)]
      (if-not (and ks vs)
        (persistent! m)
        (recur (assoc! m (first ks) (first vs))
          (next ks)
          (next vs)))))

  (defn filter-kvs [pred m] (if (nil? m) {} (reduce-kv (fn [m k v] (if (pred k v) m (dissoc m k))) m m)))
  (defn remove-kvs [pred m] (if (nil? m) {} (reduce-kv (fn [m k v] (if (pred k v) (dissoc m k) m)) m m)))

  (defn replace-in [m & ops]
    (reduce
      (fn [m ?op]
        (if-not ?op
          m ; Support conditional ops
          (let [[type ks valf] ?op
                f (if (kw-identical? type :reset) (fn [_] valf) valf)]
            (update-in m ks nil f))))
      m
      ops)))