Tinsel

Shiny threading macros with tracing. Why the name? Because.

Installation

Artifacts are published on Clojars.

Usage

Wouldn't it be nice to use the threading macros (->, ->>) but be able to see what the intermediate values are? I know, I know, that would be great, wouldn't it?

[Psst, before going any further, type this into your REPL: (require '[tinsel.core :refer [=> =>>]]).]

So what if this code:

(let [a 61
      [result trace]
      (=> (inc a)
           inc
           dec
           (fn [x] (+ x 1))
           #(- % 1)
           (+ 1)
           (* 2)
           (/ 3))]
  (clojure.pprint/pprint {:result result
                          :trace trace}))

Produced this output?

-| {:result 42,
-|  :trace
-|  [[(inc a) 62]
-|   [inc 63]
-|   [dec 62]
-|   [(fn [x] (+ x 1)) 63]
-|   [(fn* [p1__31059#] (- p1__31059# 1)) 62]
-|   [(+ 1) 63]
-|   [(* 2) 126]
-|   [(/ 3) 42]]}

By the way, tinsel supports raw function names, sugared anonymous functions e.g. #(- % 1), "regular" anonymous functions using the fn special form, integers, and keywords. As an example of the last, (let [m {:a 42}] (=> m :a)) evaluates to:

[42
 [[m {:a 42}]
  [:a 42]]]

As for integers, they work similarly to keywords, selecting the item at the given index. I implemented this feature after deciding against doing so because retrieving a particular item in a vector is not possible to do elegantly as an item in a ->> (or =>>) form, because get takes the collection as its first argument. So, (=>> [:a :b :c] 2) evaluates to [:c [[[:a :b :c] [:a :b :c]] [2 :c]]] i.e. :c plus the trace.

License

Copyright © 2013 Edwin Watkeys

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.