edw / tinsel

Tinsel: shiny threading macros with tracing

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.