Merge branch 'juxt'

docs/language/core.rst

@@ -505,6 +505,31 @@ themselves as an iterator when ``(iter x)`` is called. Contrast with
    => (iterator? (iter {:a 1 :b 2 :c 3}))
    True
 
+
+.. _juxt-fn:
+
+juxt
+----
+
+.. versionadded:: 0.12.0
+
+Usage: ``(juxt f &rest fs)``
+
+Return a function that applies each of the supplied functions to a
+single set of arguments and collects the results into a list.
+
+.. code-block:: hy
+
+   => ((juxt min max sum) (range 1 101))
+   [1, 100, 5050]
+
+   => (dict (map (juxt identity ord) "abcdef"))
+   {'f': 102, 'd': 100, 'b': 98, 'e': 101, 'c': 99, 'a': 97}
+
+   => ((juxt + - * /) 24 3)
+   [27, 21, 72, 8.0]
+
+
 .. _keyword-fn:
 
 keyword

hy/core/language.hy

@@ -298,6 +298,13 @@
   "Return true if x is an iterator"
   (isinstance x collections.Iterator))
 
+(defn juxt [f &rest fs]
+  "Return a function that apply a set of functions to same arguments and
+   collect the result into a list."
+  (setv fs (cons f fs))
+  (fn [&rest args &kwargs kwargs]
+    (list-comp (apply f args kwargs) [f fs])))
+
 (defn last [coll]
   "Return last item from `coll`"
   (get (tuple coll) -1))
@@ -483,8 +490,8 @@
     disassemble drop drop-last drop-while empty? even? every? first filter
     flatten float? fraction gensym group-by identity inc input instance?
     integer integer? integer-char? interleave interpose islice iterable?
-    iterate iterator? keyword keyword? last list* macroexpand macroexpand-1 
+    iterate iterator? juxt keyword keyword? last list* macroexpand
-    map merge-with multicombinations name neg? none? nth numeric? odd? 
+    macroexpand-1 map merge-with multicombinations name neg? none? nth
-    partition permutations pos? product range read read-str remove repeat 
+    numeric? odd? partition permutations pos? product range read read-str
-    repeatedly rest reduce second some string string? symbol? take take-nth 
+    remove repeat repeatedly rest reduce second some string string? symbol?
-    take-while xor tee zero? zip zip-longest])
+    take take-nth take-while xor tee zero? zip zip-longest])

tests/native_tests/core.hy

@@ -649,3 +649,10 @@
   (assert-true ((comp even? inc +) 1 2 3 4 5))
   (assert-true (= 5 ((comp) 5)))
   (assert (is (comp) identity)))
+
+(defn test-juxt []
+  "NATIVE: test juxt"
+  (assert-equal ((juxt min max sum) [1 2 3 4 5 6])
+                [1 6 21])
+  (assert-equal ((juxt identity) 42)
+                [42]))