:- module(leq,[leq/2]). :- use_module(library(chr)). :- chr_constraint leq/2. reflexivity @ leq(X,X) <=> true. antisymmetry @ leq(X,Y), leq(Y,X) <=> X = Y. idempotence @ leq(X,Y) \ leq(X,Y) <=> true. transitivity @ leq(X,Y), leq(Y,Z) ==> leq(X,Z). |
When the above program is saved in a file and loaded in SWI-Prolog, you can call the leq/2 constraints in a query, e.g.:
?- leq(X,Y), leq(Y,Z).
leq(_G23837, _G23841)
leq(_G23838, _G23841)
leq(_G23837, _G23838)
X = _G23837{leq = ...}
Y = _G23838{leq = ...}
Z = _G23841{leq = ...}
Yes
|
When the query succeeds, the SWI-Prolog top-level prints the content of the CHR constraint store and displays the bindings generate during the query. Some of the query variables may have been bound to attributed variables, as you see in the above example.
:- module(dom,[dom/2]). :- use_module(library(chr)). :- chr_constraint dom(?int,+list(int)). :- chr_type list(T) ---> [] ; [T|list(T)]. dom(X,[]) <=> fail. dom(X,[Y]) <=> X = Y. dom(X,L) <=> nonvar(X) | memberchk(X,L). dom(X,L1), dom(X,L2) <=> intersection(L1,L2,L3), dom(X,L3). |
When the above program is saved in a file and loaded in SWI-Prolog, you can call the dom/2 constraints in a query, e.g.:
?- dom(A,[1,2,3]), dom(A,[3,4,5]). A = 3 Yes |