assert

Lib.assert : ('a -> bool) -> 'a -> 'a

Checks that a value satisfies a predicate.

assert p x returns x if the application p x yields true. Otherwise, assert p x fails.

Failure

assert p x fails with exception HOL_ERR if the predicate p yields false when applied to the value x. If the application p x raises an exception e, then assert p x raises e.

Example

- null [];
> val it = true : bool

- assert null ([]:int list);
> val it = [] : int list

- null [1];
> false : bool

- assert null [1];
! Uncaught exception:
! HOL_ERR <poly>

See also

Lib.can, Lib.assert_exn