Since strings are lists of characters, you can use any available list function.

Lists

In Haskell, lists are what Arrays are in most other languages. Haskell has all of the general list manipulation functions, see also Data.List.

head [1,2,3]      --> 1
tail [1,2,3]      --> [2,3]
length [1,2,3]    --> 3
init [1,2,3]      --> [1,2]
last [1,2,3]      --> 3

Furthermore, Haskell supports some neat concepts.

Infinite lists

Prelude> [1..]

The list of all squares:

square x = x*x
squares = map square [1..]

But in the end, you probably don't want to use infinite lists, but make them finite. You can do this with take:

Prelude> take 10 squares
[1,4,9,16,25,36,49,64,81,100]

The list of all squares can also be written in a more comprehensive way, using list comprehensions:

squares = [x*x | x <- [1..]]

List comprehensions allow for constraints as well:

-- multiples of 3 or 5
mults = [ x | x <- [1..], mod x 3 == 0 || mod x 5 == 0 ]

Problem	Solution	Examples
combining two strings	(++)	"foo" ++ "bar" --> "foobar"
combining many strings	concat	concat ["foo", "bar", "baz"] --> "foobarbaz"

Problem	Solution	Examples
accessing the first character	head	head "foo bar baz" --> 'f'
accessing the last character	last	last "foo bar baz" --> 'z'
accessing the character at a given index	(!!)	"foo bar baz" !! 4 --> 'b'
accessing the first `n` characters	take	take 3 "foo bar baz" --> "foo"
accessing the last `n` characters	reverse , take	reverse . take 3 . reverse $ "foobar" --> "bar"
accessing the `n` characters starting from index `m`	drop, take	take 4 $ drop 2 "foo bar baz" --> "o ba"

Problem	Solution	Examples
splitting a string into a list of words	words	words "foo bar\t baz\n" --> ["foo","bar","baz"]
splitting a string into two parts	splitAt	splitAt 3 "foo bar baz" --> ("foo"," bar baz")

"foo\
\bar"               --> "foobar"

Problem	Solution	Examples
converting a character to a numeric value	ord	import Char ord 'A' --> 65
converting a numeric value to a character	chr	import Char chr 99 --> 'c'

Problem	Solution	Examples
reversing a string by characters	reverse	reverse "foo bar baz" --> "zab rab oof"
reversing a string by words	words, reverse, unwords	unwords $ reverse $ words "foo bar baz" --> "baz bar foo"
reversing a string by characters by words	words, reverse, map, unwords	unwords $ map reverse $ words "foo bar baz" --> "oof rab zab"

Problem	Solution	Examples
converting a character to upper-case	toUpper	import Char toUpper 'a' --> "A"
converting a character to lower-case	toLower	import Char toLower 'A' --> "a"
converting a string to upper-case	toUpper, map	import Char map toUpper "Foo Bar" --> "FOO BAR"
converting a string to lower-case	toLower, map	import Char map toLower "Foo Bar" --> "foo bar"

TODO

For high performance requirements (where you would typically consider C), consider using Data.ByteString.

TODO