Exercicios3.hs

module Exercicios3 where

media:: [Double] -> Double
media xs = foldl (\x y -> x + y) 0.0 xs / foldl (\x _ -> x + 1) 0.0 xs

data Correncia = Dolar | Real deriving (Show, Eq)

data Dinheiro = Dinheiro { valor:: Double, correncia:: Correncia } deriving Show

converteToDolar :: Dinheiro -> Dinheiro
converteToDolar (Dinheiro valor Dolar) = (Dinheiro valor Dolar)
converteToDolar (Dinheiro valor Real) = (Dinheiro (valor*0.18) Dolar)

operaVariosDinheiros :: [Dinheiro] -> (Dinheiro -> Dinheiro)-> [Dinheiro]
operaVariosDinheiros xs func = map func xs

pegaDolar :: Dinheiro -> Bool
pegaDolar (Dinheiro _ Dolar) = True
pegaDolar (Dinheiro _ Real) = False

pegaVariosDolar :: [Dinheiro] -> [Dinheiro]
pegaVariosDolar xs = filter(\x -> pegaDolar x) xs

somaVariosDolares :: [Dinheiro] -> Double
somaVariosDolares xs = foldl (\y (Dinheiro valor tipo) -> valor + y) 0.0 $ pegaVariosDolar xs

contaDolar :: [Dinheiro] -> Int
contaDolar xs = length $ pegaVariosDolar xs