88 lines
2.1 KiB
Plaintext
88 lines
2.1 KiB
Plaintext
%-----------------------------------------------------------------------
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sort
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CardinalDirection = struct north | east | south | west;
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map
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oppositeDirection: CardinalDirection -> CardinalDirection;
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nextDirection: CardinalDirection -> CardinalDirection;
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eqn
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oppositeDirection(north) = south;
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oppositeDirection(south) = north;
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oppositeDirection(east) = west;
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oppositeDirection(west) = east;
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nextDirection(north) = east;
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nextDirection(east) = south;
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nextDirection(south) = west;
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nextDirection(west) = north;
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%-----------------------------------------------------------------------
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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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%------------------------------------------------------------------------
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act
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show : CardinalDirection # Colour;
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changeLight: Colour;
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changedLight: Colour;
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changeDirection: CardinalDirection;
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changedDirection: CardinalDirection;
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emptyAct;
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%------------------------------------------------------------------------
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proc
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TrafficLight(direction : CardinalDirection) = TL(direction, red, true);
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TL(direction : CardinalDirection, colour : Colour, firstStart : Bool) =
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(firstStart)
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-> changeDirection(direction) . ChangeLight(direction, colour)
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<>
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show(direction, colour) .
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(colour == red)
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-> ChangeDirection(direction) . ChangeLight(direction, colour)
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<> ChangeLight(direction, colour)
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;
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ChangeDirection(direction : CardinalDirection) =
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changeDirection(nextDirection(direction)) . changeDirection(direction)
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;
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ChangeLight(direction : CardinalDirection, colour : Colour) =
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changeLight(nextColour(colour)) . TL(direction, nextColour(colour), false)
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;
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System =
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allow({
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show,
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%changeLight,
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changedLight,
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%changeDirection,
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changedDirection,
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emptyAct
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},
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comm({
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changeDirection | changeDirection -> changedDirection,
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changeLight | changeLight -> changedLight
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},
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TrafficLight(north) || TrafficLight(east) || TrafficLight(south) || TrafficLight(west) || changeDirection(north) || changeDirection(south)
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));
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init
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System
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; |