compile/unless

Syntax: (unless COND BODY ...)

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

Examples:

def invite [user]:
  unless user:
    return "missing user"
  f"sent to {user.email}"

>>> (unless False 1 2)
2
>>> (macroexpand-1 '(unless a b c))
(cond [a None] [else: b c])

See also: when.