以下显示了如何在Haskell中完成它.

基于类型siginure divide :: Int – > Int – >无论[Char] Int,您都可以看到函数除法将返回Left字符串或Right Int.

要么是代数数据结构,还有更多,你可以自己编写.

divide :: Int -> Int -> Either [Char] Int

divide dividend divisor

| (divisor == 0) = Left "Sorry, 0 is not allowed :o"

| (dividend == (minBound :: Int)) && (divisor == -1) = Left "somethig went wrong"

| otherwise = Right (dividend `div` divisor)

main = do

print (divide 4 2) -- Right 2

print (divide 4 0) -- Left "Sorry, 0 is not allowed :o"

print (divide (minBound :: Int) (-1)) -- Left "somethig went wrong"

在Haskell中,您可以将错误抛出错误“和您的错误消息”,但这会让您崩溃程序……这不是我们想要的.