compile/pass

Syntax: (pass), or a bare pass

Behaviour: A no-op expression. Expands to (begin), whose value is None. It fills a body or an arm that has to hold a form but has nothing to do.

pass also carries a bare arm, so a lone pass on a line works. The compiler/bare-control-words pragma governs that: convert (the default) accepts it, warn accepts it with a diagnostic, and error rejects it.

Examples:

>>> (if False 1 (pass))
None

>>> def try-it []:
...   try:
...     (raise (ValueError "x"))
...   except [ValueError]:
...     pass
>>> (try-it)
None

See also: compile/begin, pragma, bare-syntax.