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rely on first instantiated argument indexing in the definitions of foldl/N

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This allows shorter and more natural definitions.
This commit is contained in:
Markus Triska
2023-05-04 00:50:27 +02:00
parent c5a3ec3ba8
commit 4e60cc46a2
1 changed files with 6 additions and 12 deletions
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18
src/lib/lists.pl
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@@ -295,25 +295,19 @@ same_length([_|As], [_|Bs]) :-
% sum_list(Ls, S) :- foldl(sum_, Ls, 0, S). % sum_list(Ls, S) :- foldl(sum_, Ls, 0, S).
% ``` % ```
foldl(Goal_3, Ls, A0, A) :- foldl(_, [], A, A).
foldl_(Ls, Goal_3, A0, A). foldl(G_3, [L|Ls], A0, A) :-
foldl_([], _, A, A).
foldl_([L|Ls], G_3, A0, A) :-
call(G_3, L, A0, A1), call(G_3, L, A0, A1),
foldl_(Ls, G_3, A1, A). foldl(G_3, Ls, A1, A).
%% foldl(+Predicate, ?Ls0, ?Ls1, +A0, ?A). %% foldl(+Predicate, ?Ls0, ?Ls1, +A0, ?A).
% %
% Same as `foldl/4` but with an extra list % Same as `foldl/4` but with an extra list
foldl(Goal_4, Xs, Ys, A0, A) :-
foldl_(Xs, Ys, Goal_4, A0, A).
foldl(_, [], [], A, A).
foldl_([], [], _, A, A). foldl(G_4, [X|Xs], [Y|Ys], A0, A) :-
foldl_([X|Xs], [Y|Ys], G_4, A0, A) :-
call(G_4, X, Y, A0, A1), call(G_4, X, Y, A0, A1),
foldl_(Xs, Ys, G_4, A1, A). foldl(G_4, Xs, Ys, A1, A).
%% transpose(?Ls, ?Ts). %% transpose(?Ls, ?Ts).
% %