trues

[procedure] rem test seq

[procedure] keep test seq

[procedure] trues test seq

Seq may be a list or a string. Test is testified (see testify).

rem returns a new sequence in which elements that satisfy test are dropped. Like scheme:remove or scheme:delete.

keep returns a new sequence in which elements that doesn't satisfy test are dropped. Like scheme:filter.

trues is like keep, but the result list is constructed by the non-nil return value of test, instead of the elements that yield the non-nil return value. In arc0 trues can't take a string.

See also: testify, some, all