108 lines
2.2 KiB
Prolog
108 lines
2.2 KiB
Prolog
:- dynamic(func/3).
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:- discontiguous(func/3).
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/*
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Copyright 2018, 2019 Simon Forman
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This file is part of Thun
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Thun is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Thun is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Thun. If not see <http://www.gnu.org/licenses/>.
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*/
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/*
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Interpreter
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thun(Expression, InputStack, OutputStack)
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*/
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thun([], S, S).
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thun( [Lit|E], Si, So) :- literal(Lit), !, thun(E, [Lit|Si], So).
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thun( [Def|E], Si, So) :- def(Def, Body), !, append(Body, E, Eo), thun(Eo, Si, So).
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thun( [Func|E], Si, So) :- func(Func, Si, S), thun(E, S, So).
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thun([Combo|E], Si, So) :- combo(Combo, Si, S, E, Eo), thun(Eo, S, So).
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% Some error handling.
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thun([Unknown|E], Si, So) :-
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damned_thing(Unknown),
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write("wtf? "),
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write(Unknown), nl,
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So = [[Unknown|E]|Si].
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damned_thing(It) :-
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\+ literal(It),
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\+ def(It, _),
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\+ func(It, _, _),
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\+ combo(It, _, _, _, _).
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/*
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Literals
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*/
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literal(V) :- var(V).
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literal(I) :- number(I).
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literal([]).
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literal([_|_]).
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literal(true).
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literal(false).
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% Symbolic math expressions are literals.
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literal(_+_).
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literal(_-_).
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literal(_*_).
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literal(_/_).
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literal(_ mod _).
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% Symbolic comparisons are literals.
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literal(_>_).
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literal(_<_).
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literal(_>=_).
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literal(_=<_).
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literal(_=:=_).
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literal(_=\=_).
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/*
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Functions
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*/
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func(cons, [A, B|S], [[B|A]|S]).
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func(swap, [A, B|S], [B, A|S]).
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func(dup, [A|S], [A, A|S]).
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func(pop, [_|S], S ).
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/*
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Combinators
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*/
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combo(i, [P|S], S, Ei, Eo) :- append(P, Ei, Eo).
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combo(dip, [P, X|S], S, Ei, Eo) :- append(P, [X|Ei], Eo).
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combo(dipd, [P, X, Y|S], S, Ei, Eo) :- append(P, [Y, X|Ei], Eo).
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combo(dupdip, [P, X|S], [X|S], Ei, Eo) :- append(P, [X|Ei], Eo).
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/*
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Definitions
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*/
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def(x, [dup, i]).
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