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63 lines
1.8 KiB
Mathematica
63 lines
1.8 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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%
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% This is a cut-down version of a bug reported by Peter Hawkins.
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% Mercury rotd 2005-08-02 and before failed this because some of the
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% extra unifications required to convert the lambda expression to
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% superhomogenous form were put in the wrong spot if the body of the
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% lambda expression was impure. In particular the unifications for the
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% output arguments needed to be reordered by mode analysis so that they
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% occurred after whatever goal produces their RHS; in the case where the
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% body is impure so mode analysis could not do the necessary reordering.
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:- module impure_lambda_bug.
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:- interface.
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:- type unit ---> unit.
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:- type alpha ---> alpha.
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:- type beta ---> beta.
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% A cut down version of the original bug.
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%
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:- pred foo((impure pred(unit, unit))::out((pred(di, uo) is det))) is det.
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% A couple of other tests.
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%
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:- pred baz((pred(alpha, beta, beta))::out(pred(out, di, uo) is det)) is det.
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:- pred func_foo((impure func(unit) = unit)::out) is det.
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:- pred with_unused((impure pred(unit, unit, unit))
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::out((pred(unused, di, uo) is det))) is det.
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:- implementation.
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foo(Pred) :-
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Pred =
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( impure pred(!.A::di, !:A::uo) is det :-
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impure bar(!A)
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).
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:- impure pred bar(unit, unit).
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:- mode bar(in, out) is det.
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:- mode bar(di, uo) is det.
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bar(!A) :-
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impure private_builtin.imp.
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baz(Pred) :-
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Pred =
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( pred(R::out, A::di, B::uo) is det :-
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A = B,
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R = alpha
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).
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func_foo(Func) :-
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Func = (impure func(In) = Out :- impure bar(In, Out)).
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with_unused(Pred) :-
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Pred =
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( impure pred(_::unused, !.A::di, !:A::uo) is det :-
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impure bar(!A)
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).
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