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Merge pull request #1711 from triska/pairs_doc

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DOC: initial documentation for library(pairs) in DocLog format
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Mark Thom
2023-01-26 02:02:22 +01:00
committed by GitHub
parent 3c08eba559 996496c3f5
commit 87d6ef16f7
1 changed files with 20 additions and 0 deletions
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src/lib/pairs.pl
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@@ -1,3 +1,10 @@
/** Reasoning about pairs.
Pairs are Prolog terms with principal functor `(-)/2`. A pair
often has the form `Key-Value`. The predicates of this library
relate pairs to keys and values.
*/
:- module(pairs, [pairs_keys_values/3, :- module(pairs, [pairs_keys_values/3,
pairs_keys/2, pairs_keys/2,
pairs_values/2, pairs_values/2,
@@ -7,12 +14,25 @@
:- meta_predicate map_list_to_pairs(2, ?, ?). :- meta_predicate map_list_to_pairs(2, ?, ?).
%% pairs_keys_values(?Pairs, ?Keys, ?Values)
%
% The first argument is a list of Pairs, the second the corresponding
% Keys, and the third argument the corresponding values.
pairs_keys_values([], [], []). pairs_keys_values([], [], []).
pairs_keys_values([A-B|ABs], [A|As], [B|Bs]) :- pairs_keys_values([A-B|ABs], [A|As], [B|Bs]) :-
pairs_keys_values(ABs, As, Bs). pairs_keys_values(ABs, As, Bs).
%% pairs_keys(?Pairs, ?Keys)
%
% Same as `pairs_keys_values(Pairs, Keys, _)`.
pairs_keys(Ps, Ks) :- pairs_keys_values(Ps, Ks, _). pairs_keys(Ps, Ks) :- pairs_keys_values(Ps, Ks, _).
%% pairs_values(?Pairs, ?Values)
%
% Same as `pairs_keys_values(Pairs, _, Values)`.
pairs_values(Ps, Vs) :- pairs_keys_values(Ps, _, Vs). pairs_values(Ps, Vs) :- pairs_keys_values(Ps, _, Vs).
map_list_to_pairs(Pred, Ls, Ps) :- map_list_to_pairs(Pred, Ls, Ps) :-