layout/for-each

Symbol: layout/for-each

Use-case: Block syntax for a for-each loop with an optional else peer. The read result keeps the for-each head and is compiled by compile/for-each.

Behaviour: The header is for-each [BINDING SEQ], a binding form and the sequence it draws from. Body forms are appended to the header list with no begin wrapper, giving (for-each [BINDING SEQ] BODY...). else is the only peer gathered; its body is appended as a final (else: BODY...) clause rather than merged into the loop body. Rules: else takes no arguments, and at most one else peer may appear.

Syntax:

for-each [BINDING SEQ]:
  BODY
else:
  BODY

Examples:

for-each [x (range 0 3)]:
  (print x)
;; -> (for-each [x (range 0 3)] (print x))

for-each [x seq]:
  (print x)
else:
  done
;; -> (for-each [x seq] (print x) (else: done))

for-each [i (range 0 3)]:
  (print "item" i)
else:
  (print "for-each done")
;; prints: item 0
;; prints: item 1
;; prints: item 2
;; prints: for-each done

Also: special form for-each.