shape.hs

module Shapes
( Point(..)
, Shape(..)
, area
, nudge
, baseCircle
, baseRectangle
) where

data Point = Point Float Float deriving (Show)
data Shape = Circle Point Float | Rectangle Point Point
    deriving (Show)
area :: Shape -> Float
area (Circle _ r) = pi * r ^2
area (Rectangle (Point x1 y1) (Point x2 y2)) = (abs $ x2 - x1) * (abs $ y2 - y1)

nudge :: Shape -> Float -> Float -> Shape
nudge (Circle (Point x y) r) a b = Circle (Point (x + a) (y + b)) r
nudge (Rectangle (Point x1 y1) (Point x2 y2)) a b = Rectangle (Point (x1 + a) (y1 + a)) (Point (x2 + a) (y2 + a))  

baseCircle :: Float -> Shape
baseCircle r  = Circle (Point 0 0) r

baseRectangle :: Float -> Float -> Shape
baseRectangle width height = (Rectangle (Point 0 0) (Point width height))
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