Add frequencies to core library.

examples/frequencies.dst

@@ -1,11 +0,0 @@
-# Get the number of occurences of elements in a set
-
-(defn frequencies
- "Get the number of occurences of each value in a indexed structure."
- [ind]
- (def freqs @{})
- (loop 
-   [x :in ind]
-   (def n (get freqs x))
-   (put freqs x (if n (+ 1 n) 1)))
- freqs)

src/compiler/boot.dst

@@ -730,6 +730,16 @@ in the same manner, and so on. Useful for expressing pipelines of data."
   (:= k (next x k)))
  arr)
 
+(defn frequencies
+ "Get the number of occurences of each value in a indexed structure."
+ [ind]
+ (def freqs @{})
+ (loop 
+   [x :in ind]
+   (def n (get freqs x))
+   (put freqs x (if n (+ 1 n) 1)))
+ freqs)
+
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