Data.hs

module Graphics.X11.Turtle.Data(nameToShape, nameToSpeed) where

import Control.Arrow(second, (&&&))

nameToShape :: String -> [(Double, Double)]
nameToShape "classic" = unfold [(- 10, 0), (- 16, 6), (0, 0)]
nameToShape "turtle" = unfold [
	(- 10, 0), (- 8, 3), (- 10, 5), (- 7, 9), (- 5, 6), (0, 8), (4, 7),
	(6, 10), (8, 7), (7, 5), (10, 2), (13, 3), (16, 0)]
nameToShape name = error $ "There is no shape named " ++ name

unfold :: [(Double, Double)] -> [(Double, Double)]
unfold = uncurry (++) . (id &&& (reverse . map (second negate)))

nameToSpeed :: String -> Maybe (Maybe Double, Maybe Double)
nameToSpeed str = lookup str speedTable

speedTable :: [(String, (Maybe Double, Maybe Double))]
speedTable = [
	("fastest", (Nothing, Nothing)),
	("fast", (Just 60, Just $ pi / 3)),
	("normal", (Just 20, Just $ pi / 9)),
	("slow", (Just 10, Just $ pi / 18)),
	("slowest", (Just 3, Just $ pi / 60))
 ]