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{-# LANGUAGE ExistentialQuantification #-}
module Phi.Panel ( Panel(..)
, PanelClass(..)
, (<~>)
, separator
) where
import Data.Function
class PanelClass a where
minSize :: a -> Int
weight :: a -> Float
weight _ = 0
data Panel = forall a. PanelClass a => Panel a
instance PanelClass Panel where
minSize (Panel p) = minSize p
weight (Panel p) = weight p
data CompoundPanel = CompoundPanel Panel Panel
instance PanelClass CompoundPanel where
minSize (CompoundPanel a b) = ((+) `on` minSize) a b
weight (CompoundPanel a b) = ((+) `on` weight) a b
(<~>) :: Panel -> Panel -> Panel
a <~> b = Panel $ CompoundPanel a b
data Separator = Separator Int Float
instance PanelClass Separator where
minSize (Separator s _) = s
weight (Separator _ w) = w
separator :: Int -> Float -> Panel
separator s w = Panel $ Separator s w
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