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Estimated hours taken: 0.5 library/*.m: compiler/*.m: Undo Zoltan's bogus update of all the copyright dates. The dates in the copyright header should reflect the years in which the file was modified (and no, changes to the copyright header itself don't count as modifications).
76 lines
2.0 KiB
Mathematica
76 lines
2.0 KiB
Mathematica
%---------------------------------------------------------------------------%
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% Copyright (C) 1996-1997 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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% File: bool.m.
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% Main authors: fjh, zs.
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% Stability: medium to high.
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% This module exports the boolean type `bool' and some operations on bools.
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- module bool.
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:- interface.
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:- import_module list.
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%-----------------------------------------------------------------------------%
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% The boolean type.
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% Unlike most languages, we use `yes' and `no' as boolean constants
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% rather than `true' and `false'. This is to avoid confusion
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% with the predicates `true' and `fail'.
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:- type bool ---> no ; yes.
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:- pred bool__or(bool, bool, bool).
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:- mode bool__or(in, in, out) is det.
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:- pred bool__or_list(list(bool), bool).
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:- mode bool__or_list(in, out) is det.
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:- pred bool__and(bool, bool, bool).
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:- mode bool__and(in, in, out) is det.
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:- pred bool__and_list(list(bool), bool).
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:- mode bool__and_list(in, out) is det.
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:- pred bool__not(bool, bool).
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:- mode bool__not(in, out) is det.
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%-----------------------------------------------------------------------------%
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:- implementation.
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bool__or(yes, _, yes).
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bool__or(no, Bool, Bool).
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bool__or_list([], no).
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bool__or_list([Bool | Bools], Result) :-
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( Bool = yes ->
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Result = yes
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;
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bool__or_list(Bools, Result)
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).
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bool__and(no, _, no).
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bool__and(yes, Bool, Bool).
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bool__and_list([], yes).
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bool__and_list([Bool | Bools], Result) :-
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( Bool = no ->
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Result = no
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;
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bool__and_list(Bools, Result)
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).
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bool__not(no, yes).
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bool__not(yes, no).
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%-----------------------------------------------------------------------------%
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