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