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https://github.com/Mercury-Language/mercury.git
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d0d6d1ab2b
configure.ac:
Require step 1 to be installed.
library/prolog.m:
Add back here the definition of "is" that was deleted from int.m.
compiler/parse_goal.m:
Don't accept "is" as a synomym for "=".
NEWS:
Announce the change.
120 lines
3.5 KiB
Mathematica
120 lines
3.5 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%---------------------------------------------------------------------------%
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% Copyright (C) 1997-2003, 2005-2006, 2012 The University of Melbourne.
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% Copyright (C) 2014-2016, 2018 The Mercury team.
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% This file is distributed under the terms specified in COPYING.LIB.
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%---------------------------------------------------------------------------%
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%
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% File: prolog.m.
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% Main author: fjh.
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% Stability: high.
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%
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% This file contains predicates that are intended to help people
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% porting Prolog programs, or writing programs in the intersection
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% of Mercury and Prolog.
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%
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%---------------------------------------------------------------------------%
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%---------------------------------------------------------------------------%
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:- module prolog.
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:- interface.
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:- import_module list.
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:- import_module pair.
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:- import_module univ.
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%---------------------------------------------------------------------------%
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%
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% Prolog arithmetic operators.
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%
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:- pred T =:= T. % In Mercury, just use =
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:- mode in =:= in is semidet.
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:- pred T =\= T. % In Mercury, just use \=
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:- mode in =\= in is semidet.
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:- pred is(T, T) is det. % In Mercury, just use =
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:- mode is(uo, di) is det.
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:- mode is(out, in) is det.
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%---------------------------------------------------------------------------%
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%
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% Prolog term comparison operators.
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%
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:- pred T == T. % In Mercury, just use =
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:- mode in == in is semidet.
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:- pred T \== T. % In Mercury, just use \=
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:- mode in \== in is semidet.
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% Prolog's so-called "univ" operator, `=..'.
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% Note: this is not related to Mercury's "univ" type!
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% In Mercury, use `deconstruct.deconstruct' instead.
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:- pred T =.. univ_result.
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:- mode in =.. out is det.
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% Note that the Mercury =.. is a bit different to the Prolog one.
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% We could make it slightly more similar by overloading '.'/2,
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% but that would cause ambiguities that might prevent type
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% inference in a lot of cases.
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%
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% :- type univ_result ---> '.'(string, list(univ)).
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:- type univ_result == pair(string, list(univ)).
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% arg/3.
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% In Mercury, use arg/4 (defined in module deconstruct) instead:
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%
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% arg(ArgNum, Term, Data) :-
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% deconstruct.arg(Term, canonicalize, ArgNum - 1, Data).
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%
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:- pred arg(int::in, T::in, univ::out) is semidet.
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% det_arg/3: like arg/3, but calls error/1 rather than failing
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% if the index is out of range.
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%
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:- pred det_arg(int::in, T::in, univ::out) is det.
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%---------------------------------------------------------------------------%
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%---------------------------------------------------------------------------%
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:- implementation.
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:- import_module deconstruct.
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:- import_module int.
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:- import_module require.
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%---------------------------------------------------------------------------%
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'=:='(X, X).
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'=\\='(X, Y) :-
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X \= Y.
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is(X, X).
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'=='(X, X).
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'\\=='(X, Y) :-
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X \= Y.
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'=..'(Term, Functor - Args) :-
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deconstruct(Term, canonicalize, Functor, _Arity, Args).
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% We use module qualifiers here to avoid overriding
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% the builtin Prolog versions.
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prolog.arg(ArgumentIndex, Type, Univ) :-
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deconstruct.arg(Type, canonicalize, ArgumentIndex - 1, Arg),
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type_to_univ(Arg, Univ).
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det_arg(ArgumentIndex, Type, Argument) :-
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( if arg(ArgumentIndex, Type, Arg) then
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Argument = Arg
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else
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error("det_arg: arg failed")
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).
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%---------------------------------------------------------------------------%
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