41 lines
1.2 KiB
Plaintext
41 lines
1.2 KiB
Plaintext
:- module gray_test.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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:- implementation.
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:- import_module gray.
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:- import_module int, list, string.
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:- pred check_conversion(list(int)::in, list(gray)::out) is semidet.
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:- pred display_lists(list(int)::in, list(gray)::in, io::di, io::uo) is det.
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:- pred display_record(int::in, gray::in, io::di, io::uo) is det.
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main(!IO) :-
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Numbers = 0..31,
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( check_conversion(Numbers, Grays) ->
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io.format("%8s %8s %8s\n", [s("Number"), s("Binary"), s("Gray")], !IO),
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io.format("%8s %8s %8s\n", [s("------"), s("------"), s("----")], !IO),
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display_lists(Numbers, Grays, !IO)
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; io.write("Either conversion or back-conversion failed.\n", !IO)).
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check_conversion(Numbers, Grays) :-
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Grays = list.map(gray.from_int, Numbers),
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Numbers = list.map(gray.to_int, Grays).
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display_lists(Numbers, Grays, !IO) :-
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list.foldl_corresponding(display_record, Numbers, Grays, !IO).
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display_record(Number, Gray, !IO) :-
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gray.coerce(Gray, GrayRep),
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NumBin = string.int_to_base_string(Number, 2),
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GrayBin = string.int_to_base_string(GrayRep, 2),
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io.format("%8d %8s %8s\n", [i(Number), s(NumBin), s(GrayBin)], !IO).
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:- end_module gray_test.
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