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pl:prolog:pllib:flatten_4 [2019/06/27 15:50] |
pl:prolog:pllib:flatten_4 [2019/06/27 15:50] (aktualna) |
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| + | ====== Flatten 4 ====== | ||
| + | {{tag>lists operators}} | ||
| + | ===== Description ===== | ||
| + | Flattening a list of lists using difference-lists | ||
| + | |||
| + | **Source**: The Art of Prolog | ||
| + | ===== Download ===== | ||
| + | Program source code: {{flatten_4.pl}} | ||
| + | ===== Listing ===== | ||
| + | <code prolog> | ||
| + | /* | ||
| + | flatten(Xs,Ys) :- | ||
| + | Ys is a flattened list containing the elements in Xs. | ||
| + | */ | ||
| + | :- op(40,xfx,\). | ||
| + | |||
| + | flatten(Xs,Ys) :- flatten_dl(Xs,Ys\[]). | ||
| + | |||
| + | flatten_dl([X|Xs],Ys\Zs) :- | ||
| + | flatten_dl(X,Ys\Ys1), flatten_dl(Xs,Ys1\Zs). | ||
| + | flatten_dl(X,[X|Xs]\Xs) :- | ||
| + | constant(X), X \== []. | ||
| + | flatten_dl([],Xs\Xs). | ||
| + | |||
| + | % Program 15.2 : Flattening a list of lists using difference-lists | ||
| + | </code> | ||
| + | ===== Comments ===== | ||
