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61 lines
1.6 KiB
Mathematica
61 lines
1.6 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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:- module higher_order_syntax.
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:- interface.
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:- import_module io.
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:- import_module list.
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:- import_module std_util.
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:- pred main(io::di, io::uo) is det.
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:- func map_f(func(X) = Y, list(X)) = list(Y).
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:- mode map_f(func(in) = out is det, in) = out is det.
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:- mode map_f(func(in) = out is semidet, in) = out is semidet.
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:- pred map_p(pred(X, Y), list(X), list(Y)).
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:- mode map_p(pred(in, out) is det, in, out) is det.
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:- mode map_p(pred(in, out) is semidet, in, out) is semidet.
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:- mode map_p(pred(in, out) is multi, in, out) is multi.
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:- mode map_p(pred(in, out) is nondet, in, out) is nondet.
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%---------------------------------------------------------------------------%
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:- implementation.
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:- import_module int.
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main -->
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{ L1 = [1, 2, 3] },
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{ L2 = map_f((func(X::in) = (Y::out) is det :- Y = 2*X), L1) },
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{ map_p((pred(X::in, Y::out) is det :- Y = 2*X), L2, L3) },
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{ L4 = map_f((func(X2) = Y2 :- Y2 = 5*X2), L3) },
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{ L = map_f(func(X3) = 10*X3, L4) },
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{ Foldit =
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( pred(IO0::di, IO::uo) is det :-
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list.foldl(io.write_int, L, IO0, IO)
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)
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},
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Foldit,
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{ Write = io.write_string },
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Write("\n"),
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( if { doit(semidet_succeed) } then
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Write("Yes.\n")
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else
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Write("No.\n")
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).
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map_f(_, []) = [].
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map_f(F, [H0 | T0]) = [F(H0) | map_f(F, T0)].
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map_p(_, [], []).
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map_p(P, [X | Xs], [Y | Ys]) :-
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P(X, Y),
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map_p(P, Xs, Ys).
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:- pred doit(pred).
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:- mode doit((pred) is semidet).
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doit(P) :-
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P.
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