compile/when

Syntax: (when COND BODY ...)

Behaviour: Expands to (cond [COND BODY ...] [else: None]). When COND is truthy the body forms run in order and the last is the value; otherwise the value is None.

Examples:

(when (> n 0)
  (print n)
  n)

when (> n 0):
  print n
  n

>>> (macroexpand-1 '(when a b c))
(cond [a b c] [else: None])

See also: unless for the inverted test, if for two arms.