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{-# OPTIONS_CYMAKE -F --pgmF=currypp --optF=defaultrules #-}
import Test.EasyCheck
-- Dijsktra's Dutch National Flag problem with functional patterns,
-- default rule declared as a deterministic function:
data Color = Red | White | Blue
solveD :: [Color] -> DET [Color]
solveD (x++[White]++y++[Red ]++z) = solveD (x++[Red ]++y++[White]++z)
solveD (x++[Blue ]++y++[Red ]++z) = solveD (x++[Red ]++y++[Blue ]++z)
solveD (x++[Blue ]++y++[White]++z) = solveD (x++[White]++y++[Blue ]++z)
solveD'default flag = flag
iflag = [White,Red,White,Blue,Red,Blue,White]
main = solveD iflag
--> [Red,Red,White,White,White,Blue,Blue]
test_solveD = solveD iflag -=- [Red,Red,White,White,White,Blue,Blue]
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