Add each.

examples/3sum.dst

@@ -2,7 +2,7 @@
 (import "examples/iterators.dst")
 
 (defn sum3
- "Solve the 3SUM problem O(n^2) time."
+ "Solve the 3SUM problem in O(n^2) time."
  [s]
  (def tab @{})
  (def solutions @{})

examples/frequencies.dst

@@ -4,7 +4,7 @@
  "Get the number of occurences of each value in a indexed structure."
  [ind]
  (def freqs @{})
- (map (fn [x] 
+ (each (fn [x] 
     (let [n (get freqs x)]
      (put freqs x (if n (+ 1 n) 1)))) ind)
  freqs)

src/compiler/boot.dst

@@ -400,6 +400,27 @@ the same type as the input sequence."
    (array-push res (apply1 f args))))
  res)
 
+(defn each
+ "Map a function over every element in an array or tuple but do not
+return a new indexed type."
+ [f & inds]
+ (def ninds (length inds))
+ (if (= 0 ninds) (error "expected at least 1 indexed collection."))
+ (var limit (length (get inds 0)))
+ (for [i 0 ninds]
+  (def l (length (get inds i)))
+  (if (< l limit) (:= limit l)))
+ (def [i1 i2 i3 i4] inds)
+ (switch ninds
+  1 (for [i 0 limit] (f (get i1 i)))
+  2 (for [i 0 limit] (f (get i1 i) (get i2 i)))
+  3 (for [i 0 limit] (f (get i1 i) (get i2 i) (get i3 i)))
+  4 (for [i 0 limit] (f (get i1 i) (get i2 i) (get i3 i) (get i4 i)))
+  (for [i 0 limit]
+   (def args @[])
+   (for [j 0 ninds] (array-push args (get (get inds j) i)))
+   (apply1 f args))))
+
 (defn mapcat
  "Map a function over every element in an array or tuple and
 use array to concatenate the results. Returns the same