Created
August 11, 2012 21:30
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Finding the minimum in a list in Prolog
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% This version doesn't work. | |
min_wrong([Item], Item). | |
min_wrong([Item | List], Item) :- | |
min_wrong(List, List_Answer), | |
Item =< List_Answer. | |
min_wrong([_Item | List], Answer) :- | |
min_wrong(List, Answer). | |
% Output: | |
% | |
% [debug] ?- min_wrong([1,2,3], Answer). | |
% Answer = 1 ; | |
% Answer = 1 ; | |
% Answer = 2 ; | |
% Answer = 3 ; | |
% false. | |
% This version does work | |
min([Item], Item). | |
min([Item | List], Item) :- | |
min(List, List_Answer), | |
Item =< List_Answer, !. | |
min([_Item | List], Answer) :- | |
min(List, Answer). | |
% Here's the built-in function | |
min_list([H|T], Min) :- | |
min_list(T, H, Min). | |
min_list([], Min, Min). | |
min_list([H|T], Min0, Min) :- | |
Min1 is min(H, Min0), | |
min_list(T, Min1, Min). |
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