32 lines
566 B
Plaintext
32 lines
566 B
Plaintext
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sort
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CardinalDirection = struct north | east | south | west;
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sort
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Colour = struct red | green | yellow;
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map
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nextColour: Colour -> Colour;
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eqn
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nextColour(red) = green;
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nextColour(green) = yellow;
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nextColour(yellow) = red;
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act
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show : CardinalDirection # Colour;
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proc
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TrafficLight(direction : CardinalDirection) = TF(direction, red);
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TF(direction : CardinalDirection, colour : Colour) =
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show(direction, colour).
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TF(direction, nextColour(colour))
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;
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init
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TrafficLight(north) || TrafficLight(east) || TrafficLight(south) || TrafficLight(west)
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;
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