104 lines
2.0 KiB
Plaintext
104 lines
2.0 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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otherDirection : CardinalDirection -> CardinalDirection;
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eqn
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otherDirection(north) = south;
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otherDirection(south) = north;
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otherDirection(east) = west;
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otherDirection(west) = east;
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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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safeColour: 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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safeColour(green) = red;
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safeColour(red) = green;
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safeColour(yellow) = red;
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%------------------------------------------------------------------------
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sort
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Map = K -> V;
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map
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_Map: V -> Map;
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var
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k: K;
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v: V;
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eqn
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_Map(v)(k) = v;
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sort
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K = CardinalDirection;
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V = Colour;
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map
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combinations: Map;
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%------------------------------------------------------------------------
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act
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show : CardinalDirection # Colour;
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seeColour : CardinalDirection # Colour;
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colourSeen : CardinalDirection # Colour;
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crossingUnsafe : Colour # Colour # Colour # Colour;
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%------------------------------------------------------------------------
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proc
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TrafficLight(direction : CardinalDirection) = TL(direction, red);
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TL(direction : CardinalDirection, colour : Colour) =
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show(direction, colour) . TL(direction, nextColour(colour))
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;
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Monitor(status : Map) =
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((status(north) in {green, yellow} || status(south) in {green, yellow}) && (status(east) in {green, yellow} || status(west) in {green, yellow}))
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-> crossingUnsafe(status(north), status(east), status(south), status(west)) . delta
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<>
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sum direction : CardinalDirection.(
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sum c : Colour .
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seeColour(direction, c) .
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Monitor(status= status[direction -> c])
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);
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System =
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allow({
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colourSeen,
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crossingUnsafe
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},
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comm({
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show | seeColour -> colourSeen
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},
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TrafficLight(north) || TrafficLight(east) || TrafficLight(south) || TrafficLight(west) || Monitor(_Map(red))
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));
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init
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System
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; |