104 lines
2.7 KiB
Haskell
104 lines
2.7 KiB
Haskell
-- | This module defines some example worlds and programs for testing
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-- your Karel interpreter.
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module KarelExamples where
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import Prelude hiding (Either(..))
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import KarelSyntax
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import KarelState
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--
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-- * Trivial worlds
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--
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-- | A world that is all walls.
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wallWorld :: World
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wallWorld = const Nothing
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-- | A world that is completely empty of walls and beepers.
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emptyWorld :: World
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emptyWorld = const (Just 0)
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-- | A robot that starts at the origin, facing north, with the
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-- given number of beepers.
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originBot :: Int -> Robot
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originBot b = ((0,0),North,b)
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--
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-- * Demo world
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--
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-- | A 10x5 room with some beepers in a line, illustrated below.
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--
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-- XXXXXXXXXXXX
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-- X X
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-- X X
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-- X X
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-- X @ 2 3 4 X
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-- X X
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-- XXXXXXXXXXXX
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--
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-- The @ symbol is coordinate (1,1).
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-- Clear spaces are from (0,0) to (9,4).
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-- There are beepers at the following locations:
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-- * 2 beepers at (4,1)
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-- * 3 beepers at (6,1)
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-- * 4 beepers at (8,1)
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--
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demoWorld :: World
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demoWorld (4,1) = Just 2
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demoWorld (6,1) = Just 3
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demoWorld (8,1) = Just 4
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demoWorld (x,y) | x >= 0 && x < 10 &&
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y >= 0 && y < 5 = Just 0
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| otherwise = Nothing
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-- | An initial robot state for the demo world. The robot starts at
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-- (1,1), facing East, with 1 beeper in its bag.
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demoBot :: Robot
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demoBot = ((1,1),East,1)
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--
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-- * Program generators
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--
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-- | Generate a program that does the following n times:
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-- 1. moves in a straight line until it finds a beeper
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-- 2. picks it up
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-- 3. returns to its original position and facing.
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fetcher :: Int -> Prog
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fetcher n = ([("fetch",fetch)], main)
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where
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fetch = Block
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[ While (Not Beeper) -- do until we find a beeper:
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(If (Clear Front) -- can we move forward?
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Move -- if yes, then do it
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Shutdown) -- if not, shut down
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, PickBeeper ]
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main = Block
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[ Iterate n $ Block -- repeat n times:
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[ PutBeeper -- put a beeper down to mark our place
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, Move -- move forward one space
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, Call "fetch" -- go get a new beeper
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, Turn Back -- turn around
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, Move -- move forward one space
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, Call "fetch" -- go back to where we started
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, Turn Back ] -- turn back to our initial facing
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, Shutdown ]
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-- | Generates a statement that moves the robot in a rectangle of
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-- the given dimensions.
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rectangle :: Int -> Int -> Stmt
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rectangle w h = Block
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[ While (Not (Facing North)) (Turn Right)
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, Iterate h Move
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, Turn Right
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, Iterate w Move
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, Turn Right
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, Iterate h Move
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, Turn Right
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, Iterate w Move
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, Turn Right ]
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