HaskellLambdaCase
示例
语法扩展使您可以\case代替\arg->caseargof。
考虑以下函数定义：
dayOfTheWeek :: Int -> String dayOfTheWeek 0 = "Sunday" dayOfTheWeek 1 = "Monday" dayOfTheWeek 2 = "Tuesday" dayOfTheWeek 3 = "Wednesday" dayOfTheWeek 4 = "Thursday" dayOfTheWeek 5 = "Friday" dayOfTheWeek 6 = "Saturday"
如果要避免重复函数名称，可以编写类似以下内容的内容：
dayOfTheWeek :: Int -> String
dayOfTheWeek i = case i of
0 -> "Sunday"
1 -> "Monday"
2 -> "Tuesday"
3 -> "Wednesday"
4 -> "Thursday"
5 -> "Friday"
6 -> "Saturday"使用LambdaCase扩展，您可以将其编写为函数表达式，而无需命名参数：
{-# LANGUAGE LambdaCase #-}
dayOfTheWeek :: Int -> String
dayOfTheWeek = \case
0 -> "Sunday"
1 -> "Monday"
2 -> "Tuesday"
3 -> "Wednesday"
4 -> "Thursday"
5 -> "Friday"
6 -> "Saturday"