Haskell理解流程

Question

我是 Haskell 新手，我正在尝试编写一个字符串分割函数

delim = '|'
splitStr::[Char]->[[Char]]->[[Char]]
splitStr list y                 
                | sL > 0 && sL < length(list) = splitStr (drop (sL+1) list) [subList]++y
                | otherwise = [subList]++y
                where 
                    subList = takeWhile (\x -> x /= delim) list 
                    sL = length(subList)

split s = splitStr s []

但是，上面的代码总是以相反的顺序返回字符串

Main> split "foo|bar|java|python"
["python","java","bar","foo"]

从y++[subList]更改为[subList]++y仍然给出相同的结果。我知道也许有更好的方法可以做到这一点，但我想知道为什么会发生上述情况。

Answer 1

splitStr (drop (sL+1) list) [subList]++y

这被解析为(splitStr (drop (sL+1) list) [subList])++y。您想要的可能是 splitStr (drop (sL+1) list) ([subList]++y)。