6a455d2866
Examples:
?- chars_si("hello").
true.
?- chars_si(5).
false.
?- chars_si([a,b,c|Rs]).
error(instantiation_error,sort/2).
53 lines
1.3 KiB
Prolog
53 lines
1.3 KiB
Prolog
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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Safe type tests
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===============
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"si" stands for "sufficiently instantiated".
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These predicates:
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- throw instantiation errors if the argument is
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not sufficiently instantiated to make a sound decision
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- succeed if the argument is of the specified type
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- fail otherwise.
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For instance, atom_si(A) yields an *instantiation error* if A is a
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variable. This is logically sound, since in that case the argument
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is not sufficiently instantiated to make any decision.
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The definitions are taken from:
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https://stackoverflow.com/questions/27306453/safer-type-tests-in-prolog
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"si" can also be read as "safe inference", so possibly also other
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predicates are candidates for this library.
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- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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:- module(si, [atom_si/1,
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integer_si/1,
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atomic_si/1,
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list_si/1,
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chars_si/1]).
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:- use_module(library(lists)).
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atom_si(A) :-
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functor(A, _, 0), % for the instantiation error
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atom(A).
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integer_si(I) :-
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functor(I, _, 0),
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integer(I).
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atomic_si(AC) :-
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functor(AC,_,0).
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list_si(L) :-
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\+ \+ length(L, _),
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sort(L, _).
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chars_si(Cs) :-
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list_si(Cs),
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'$is_partial_string'(Cs).
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