78 lines
2.0 KiB
Prolog
78 lines
2.0 KiB
Prolog
|
|
:- system_module( '$_lists', [], []).
|
|
|
|
:- '$set_yap_flags'(11,1). % source.
|
|
|
|
% memberchk(+Element, +Set)
|
|
% means the same thing, but may only be used to test whether a known
|
|
% Element occurs in a known Set. In return for this limited use, it
|
|
% is more efficient when it is applicable.
|
|
|
|
/** @pred memberchk(+ _Element_, + _Set_)
|
|
|
|
|
|
As member/2, but may only be used to test whether a known
|
|
_Element_ occurs in a known Set. In return for this limited use, it
|
|
is more efficient when it is applicable.
|
|
|
|
|
|
*/
|
|
lists:memberchk(X,[X|_]) :- !.
|
|
lists:memberchk(X,[_|L]) :-
|
|
lists:memberchk(X,L).
|
|
|
|
% member(?Element, ?Set)
|
|
% is true when Set is a list, and Element occurs in it. It may be used
|
|
% to test for an element or to enumerate all the elements by backtracking.
|
|
% Indeed, it may be used to generate the Set!
|
|
|
|
/** @pred member(? _Element_, ? _Set_)
|
|
|
|
|
|
True when _Set_ is a list, and _Element_ occurs in it. It may be used
|
|
to test for an element or to enumerate all the elements by backtracking.
|
|
|
|
|
|
*/
|
|
lists:member(X,[X|_]).
|
|
lists:member(X,[_|L]) :-
|
|
lists:member(X,L).
|
|
|
|
/** @pred append(? _List1_,? _List2_,? _List3_)
|
|
|
|
|
|
Succeeds when _List3_ unifies with the concatenation of _List1_
|
|
and _List2_. The predicate can be used with any instantiation
|
|
pattern (even three variables).
|
|
|
|
|
|
*/
|
|
lists:append([], L, L).
|
|
lists:append([H|T], L, [H|R]) :-
|
|
lists:append(T, L, R).
|
|
|
|
|
|
:- '$set_yap_flags'(11,0). % :- no_source.
|
|
|
|
% lists:delete(List, Elem, Residue)
|
|
% is true when List is a list, in which Elem may or may not occur, and
|
|
% Residue is a copy of List with all elements identical to Elem lists:deleted.
|
|
|
|
/** @pred delete(+ _List_, ? _Element_, ? _Residue_)
|
|
|
|
|
|
True when _List_ is a list, in which _Element_ may or may not
|
|
occur, and _Residue_ is a copy of _List_ with all elements
|
|
identical to _Element_ deleted.
|
|
|
|
|
|
*/
|
|
lists:delete([], _, []).
|
|
lists:delete([Head|List], Elem, Residue) :-
|
|
Head == Elem, !,
|
|
lists:delete(List, Elem, Residue).
|
|
lists:delete([Head|List], Elem, [Head|Residue]) :-
|
|
lists:delete(List, Elem, Residue).
|
|
|
|
|