Is it possible if given a string I could get each character composing that string?
3 Answers
In Haskell, strings are just (linked) 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, provided that 0 <= n < length mystring.
5 Comments
hammar
map sum . group . sort is ill-typed for strings. Perhaps you meant something like map (head &&& length) . group . sort?
user997112
So say I passed a string in as a parameter to a function, how would I actually access each char? using map?
user997112
@FUZxxl, what happens if you're using an abstract data type, which is not technically a string, but is a string..... how do you get the characters then?
fuz
@user997112 I don't understand your question. Except some esoteric extensions to Haskell, anything declared as
"abc" or of type String or equally [Char] is a String as described above.
alternative
@FUXxxl he means
newtype String2 = String2 String, but not exporting the constructor, I thinkWell, the question does say he wants an array:
import Data.Array
stringToArray :: String -> Array
stringToArray s = listArray (0, length s - 1) s
1 Comment
setholopolus
This is what I came looking for. In fact, this is the correct answer to the question, even if it wasn't what the OP intended.
id.