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Merge pull request #1677 from aarroyoc/docs-dif

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Compatible Doclog docs for library(dif)
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Mark Thom
2023-01-13 07:50:17 +01:00
committed by GitHub
parent 3a4aa2a541 07f358c91b
commit a80aab48cd
1 changed files with 19 additions and 0 deletions
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19
src/lib/dif.pl
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@@ -1,3 +1,8 @@
/**
Provides predicate dif/2. dif/2 is a constraint that is true only if both of its
arguments are different terms.
*/
:- module(dif, [dif/2]). :- module(dif, [dif/2]).
:- use_module(library(atts)). :- use_module(library(atts)).
@@ -38,6 +43,20 @@ verify_attributes(Var, Value, Goals) :-
% Probably the world's worst dif/2 implementation. I'm open to % Probably the world's worst dif/2 implementation. I'm open to
% suggestions for improvement. % suggestions for improvement.
%% dif(?X, ?Y).
%
% True iff X and Y are different terms. Unlike \\=/2, dif/2 is more declarative because if X and Y can
% unify but they're not yet equal, the decision is delayed, and prevents X and Y to become equal later.
% Examples:
%
% ?- dif(a, a).
% false.
% ?- dif(a, b).
% true.
% ?- dif(X, b).
% dif:dif(X,b).
% ?- dif(X, b), X = b.
% false.
dif(X, Y) :- dif(X, Y) :-
X \== Y, X \== Y,
( X \= Y -> true ( X \= Y -> true