小编Ste*_*eve的帖子

在下面的Haskell代码中,如何更简洁地编写它？是否有必要列出所有四个条件,还是可以通过更紧凑的模式进行总结？例如,有没有一种方法可以利用Haskell已经知道如何添加一个浮点数和一个int,而不必手动指定fromIntegral？

data Signal = SignalInt Int | SignalFloat Float | Empty deriving (Show)

sigAdd :: Signal -> Signal -> Signal
sigAdd (SignalInt a) (SignalInt b) = SignalInt (a + b)
sigAdd (SignalInt a) (SignalFloat b) = SignalFloat ((fromIntegral a) + b)
sigAdd (SignalFloat a) (SignalInt b) = SignalFloat (a + (fromIntegral b))
sigAdd (SignalFloat a) (SignalFloat b) = SignalFloat (a + b)

main :: IO ()
main = do
  putStrLn (show (sigAdd (SignalFloat 2) (SignalInt 5)))