Haskell从字符串中获取字符数组？

Question

如果给出一个字符串，我可以让每个字符组成该字符串吗？

Answer 1

In Haskell, strings are just (liked) lists of characters; you can find the line

type String = [Char]

somewhere in the source of every Haskell implementation. That makes tasks such as finding the first occurence of a certain character ( elemIndex 'a' mystring ) or calculating the frequency of each character ( map (head &&& length) . group . sort ) trivial.

Because of this, you can use the usual syntax for lists with strings, too. Actually, "foo" is just sugar for ['f','o','o'] , which in turn is just sugar for 'f' : 'o' : 'o' : [] . You can pattern match, map and fold on them as you like. For instance, if you want to get the element at position n of mystring , you could use mystring !! n mystring !! n , provided that 0 <= n < length mystring .

Answer 2

Well, the question does say he wants an array:

import Data.Array
stringToArray :: String -> Array
stringToArray s = listArray (0, length s - 1) s

Answer 3

The string type is just an alias for [Char] so you don't need to do anything.

Prelude> tail "Hello"
"ello"
Prelude> ['H', 'e', 'l', 'l', 'o']
"Hello"
Prelude> "Hello" !! 4
'o'