Created
July 6, 2016 16:16
Functional Kats Robot simulator kata
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module Lib where | |
import Control.Arrow (first, second) | |
data Dir = N | E | S | W deriving (Show, Enum, Bounded) | |
type Pos = (Int, Int) | |
data Robot = Robot Dir Pos deriving Show | |
right :: Dir -> Dir | |
right W = N | |
right d = succ d | |
left :: Dir -> Dir | |
left N = W | |
left d = pred d | |
-- Dir is direction robot currently facing | |
advance :: Dir -> Pos -> Pos | |
advance N = second succ | |
advance E = first succ | |
advance S = second pred | |
advance W = first pred | |
interpretC :: Char -> Robot -> Robot | |
interpretC 'R' (Robot d p) = (Robot (right d) p) | |
interpretC 'L' (Robot d p) = (Robot (left d) p) | |
interpretC 'A' (Robot d p) = (Robot d (advance d p)) | |
interpretC _ _ = error "undefined movement command" | |
interpretS :: String -> Robot -> Robot | |
interpretS s r = foldl (flip interpretC) r s | |
test :: IO () | |
test = do | |
let r = Robot N (7,3) | |
let r' = interpretS "RAALAL" r | |
print r' |
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