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Estimated hours taken: 0.1 Branches: main library/*.m: Make it easier for vi to jump past the initial comments at the head of a module.
114 lines
3.3 KiB
Mathematica
114 lines
3.3 KiB
Mathematica
%---------------------------------------------------------------------------%
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% Copyright (C) 1997-2003, 2005-2006 The University of Melbourne.
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% This file may only be copied under the terms of the GNU Library General
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% Public License - see the file COPYING.LIB in the Mercury distribution.
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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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% Prolog arithmetic operators.
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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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/*******
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is/2 is currently defined in int.m, for historical reasons.
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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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% Prolog term comparison operators.
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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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%
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% Note that the Mercury =.. is a bit different to the Prolog
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% one. 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. In Mercury, use argument/3 (defined in module std_util)
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% instead:
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% arg(ArgNum, Term, Data) :- argument(Term, 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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% we use module qualifiers here to avoid
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% overriding the builtin Prolog versions
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'=='(X, X).
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'\\=='(X, Y) :- X \= Y.
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'=:='(X, X).
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'=\\='(X, Y) :- 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 a module qualifier here to avoid
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% overriding the builtin Prolog version
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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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( arg(ArgumentIndex, Type, Arg) ->
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Argument = Arg
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;
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error("det_arg: arg failed")
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).
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%-----------------------------------------------------------------------------%
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