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{-# LANGUAGE ScopedTypeVariables #-}
module M () where
import Data.Bits ((.&.))
bitsSet :: Int -> Int -> Bool
bitsSet mask i
= (i .&. mask == mask)
class Eq b => BitMask b where
assocBitMask :: [(b,Int)]
fromBitMask :: Int -> b
fromBitMask i
= walk assocBitMask
where
walk [] = error "Graphics.UI.WX.Types.fromBitMask: empty list"
walk [(x,0)] = x
walk ((x,m):xs) | bitsSet m i = x
| otherwise = walk xs
data Align = AlignLeft
| AlignCentre
deriving Eq
instance BitMask Align where
assocBitMask
= [(AlignCentre,512)
,(AlignLeft, 256)
]
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