assert_exn

Lib.assert_exn : ('a -> bool) -> 'a -> exn -> 'a

Checks that a value satisfies a predicate.

assert_exn p x e returns x if the application p x evaluates to true. Otherwise, assert_exn p x e raises e

Failure

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

Example

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

- assert_exn null ([]:int list) (Fail "non-empty list");
> val it = [] : int list

- null [1];
> false : bool

- assert_exn null [1] (Fail "non-empty list");;
! Uncaught exception:
! Fail  "non-empty list"

See also

Lib.can, Lib.assert