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;; Copyright (c) Jason Wolfe. All rights reserved. The use and
;; distribution terms for this software are covered by the Eclipse Public
;; License 1.0 ( which can
;; be found in the file epl-v10.html at the root of this distribution. By
;; using this software in any fashion, you are agreeing to be bound by the
;; terms of this license. You must not remove this notice, or any other,
;; from this software.
;; map_utils.clj
;; Utilities for operating on Clojure maps.
;; jason at w01fe dot com
;; Created 25 Feb 2009
#^{:author "Jason Wolfe, Chris Houser",
:doc "Utilities for operating on Clojure maps."}
(defmacro lazy-get
"Like get, but doesn't evaluate not-found unless it is needed."
[map key not-found]
`(if-let [pair# (find ~map ~key)]
(val pair#)
(defn safe-get
"Like get, but throws an exception if the key is not found."
[map key]
(lazy-get map key
(throw (IllegalArgumentException. (format "Key %s not found in %s" key map)))))
(defn safe-get-in
"Like get-in, but throws an exception if any key is not found."
[map ks]
(reduce safe-get map ks))
; by Chouser:
(defn deep-merge-with
"Like merge-with, but merges maps recursively, applying the given fn
only when there's a non-map at a particular level.
(deepmerge + {:a {:b {:c 1 :d {:x 1 :y 2}} :e 3} :f 4}
{:a {:b {:c 2 :d {:z 9} :z 3} :e 100}})
-> {:a {:b {:z 3, :c 3, :d {:z 9, :x 1, :y 2}}, :e 103}, :f 4}"
[f & maps]
(fn m [& maps]
(if (every? map? maps)
(apply merge-with m maps)
(apply f maps)))
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