zip(?List1:list, ?List2:list, ?ListOfLists:list(list)) is semidet

Zips two lists, List1 and List2, where each element from the first list pairs with the same element from the second list. Alternatively unzips one list of lists into two lists.

Only succeeds if the lists and sub-lists have matching lengths.

 pairs(?Items:list, ?Pairs:list(pair)) is semidet

Pairs up list elements, or unpairs them in (-, +) mode. Pairs are First-Second terms where First and Second match two consecutive Items. Unifies a list with its paired list.

There needs to be an even number of list elements. This requirement proceeds from the definition of pairing; it pairs the entire list including the last. The predicate fails otherwise.

 indexed(?Items:list, ?Pairs:list(pair)) is semidet

 indexed(?List1:list, ?Index:integer, ?List2:list) is semidet

Unifies List1 of items with List2 of pairs where the first pair element is an increasing integer index. Index has some arbitrary starting point, or defaults to 1 for one-based indexing. Unification works in all modes.

 take_at_most(+Length:integer, +List0, -List) is semidet

List takes at most Length elements from List0. List for Length of zero is always an empty list, regardless of the incoming List0. List is always empty for an empty List0, regardless of Length. Finally, elements from List0 unify with List until either Length elements have been seen, or until no more elements at List0 exist.

 select1(+Indices, +List0, -List) is det

Selects List elements by index from List0. Applies nth1/3 to each element of Indices. The 1 suffix of the predicate name indicates one-based Indices used for selection. Mirrors select/3 except that the predicate picks elements from a list by index rather than by element removal.

See also

- nth1/3

- select/3

 select_apply1(+Indices, :Goal, +Extra) is nondet

Selects one-based index arguments from Extra and applies these extras to Goal.

See also

- apply/2

 comb2(?List1, ?List2) is nondet

Unifies List2 with all combinations of List1. The length of List2 defines the number of elements in List1 to take at one time. It follows that length of List1 must not be less than List2. Fails otherwise.

See also

- http://kti.ms.mff.cuni.cz/~bartak/prolog/combinatorics.html

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 indexed(Arg1, Arg2, Arg3)