Merge pull request #788 from nicolas-p/ap-pipe-ap-compose

Added ap-pipe and ap-compose macros

AUTHORS

@@ -60,5 +60,6 @@
 * Shrayas Rajagopal <shrayasr@gmail.com>
 * Shenyang Zhao <dev@zsy.im>
 * Zack M. Davis <code@zackmdavis.net>
+* Nicolas Pénet <z.nicolas@gmail.com>
 * Adrià Garriga Alonso <adria@monkingme.com>
 * Antony Woods <antony@teamwoods.org>

docs/contrib/anaphoric.rst

@@ -195,3 +195,36 @@ first element instead. This exposes the element being iterated as
 
    =>(ap-reduce (+ it acc) (range 10))
    45
+
+
+.. _ap-pipe:
+
+ap-pipe
+=========
+
+Usage ``(ap-pipe value form1 form2 ...)``
+
+Applies several forms in series to a value from left to right. The special variable ``ìt`` in each form is replaced by the result of the previous form.
+
+.. code-block:: hy
+
+   => (ap-pipe 3 (+ it 1) (/ 5 it))
+   1.25
+   => (ap-pipe [4 5 6 7] (list (rest it)) (len it))
+   3
+
+
+.. _ap-compose:
+
+ap-compose
+=========
+
+Usage ``(ap-compose form1 form2 ...)``
+
+Returns a function which applies several forms in series from left to right. The special variable ``ìt`` in each form is replaced by the result of the previous form.
+
+.. code-block:: hy
+
+   => (def op (ap-compose (+ it 1) (* it 3)))
+   => (op 2)
+   9

hy/contrib/anaphoric.hy

@@ -109,3 +109,15 @@
     `(let [[acc ~initial-value]]
        (ap-each ~lst (setv acc ~form))
        acc)))
+
+
+(defmacro ap-pipe [var &rest forms]
+  "Pushes a value through several forms.
+  (Anaphoric version of -> and ->>)"
+  (if (empty? forms) var
+      `(ap-pipe (let [[it ~var]] ~(first forms)) ~@(rest forms))))
+
+
+(defmacro ap-compose [&rest forms]
+  "Returns a function which is the composition of several forms."
+  `(fn [var] (ap-pipe var ~@forms)))

tests/native_tests/contrib/anaphoric.hy

@@ -103,3 +103,13 @@
   (assert-equal (ap-reduce (+ acc " on " it) ["Hy" "meth"])
 		"Hy on meth")
   (assert-equal (ap-reduce (+ acc it) [] 1) 1))
+  
+(defn test-ap-pipe []
+  "NATIVE: testing anaphoric pipe"
+  (assert-equal (ap-pipe 2 (+ it 1) (* it 3)) 9)
+  (assert-equal (ap-pipe [4 5 6 7] (list (rest it)) (len it)) 3))
+  
+(defn test-ap-compose []
+  "NATIVE: testing anaphoric compose"  
+  (assert-equal ((ap-compose (+ it 1) (* it 3)) 2) 9)
+  (assert-equal ((ap-compose (list (rest it)) (len it)) [4 5 6 7]) 3))