ord_select ?
"Nicos Angelopoulos" <[email protected]>
| Newsgroups | gmane.comp.ai.prolog.swi |
|---|---|
| Message-ID | <20140212110713.222e8445@ampelos> |
Dear all, in library library(ordsets) I would like to have the same behaviour as select/3 for lists, in that if the element is not in the set the predicate should fail. That is ?- select( a, [a,b,c], R ). R = [b, c] ; ?- select( d, [a,b,c], R ). false. ord_del_element/3 is the closest thing as far as i can see, but it does not fail if the element is not in the set. ?- ord_del_element( [a,b,c], d, R ). R = [a, b, c]. 1. am i missing the correct predicate to achieve this ? 2. would it make sense to include some such like predicate to the library? Regards, Nicos Angelopoulos --- http://stoics.org.uk/~nicos/