Also xs is of what type? list of values? So does this mean x is an element and xs must be of type list
Exactly. x is of type Char and xs is of type [Char]. The list concatenation function (++) expects both of its arguments to be lists, so that's the reason you need to turn a Char x into a list containing only one value ([x]). — Sincerely yours, Daniil Frumin Angus Comber <anguscomber@gmail.com="mailto:anguscomber@gmail.com">> wrote: I am reading Learn you a Haskell for great good and on page 40 - as-patterns. I have changed the example slightly to be: firstLetter :: String -> String firstLetter "" = "Empty string, oops" firstLetter all@(x:xs) = "The first letter of " ++ all ++ " is " ++ [x] ++ " otherbit " ++ xs Then can use like this: *Main> firstLetter "Qwerty" "The first letter of Qwerty is Q otherbit werty" But I was confused about the difference between [x] and x and why I have to use [x] in the above example. For example if I change to firstLetter :: String -> String firstLetter "" = "Empty string, oops" firstLetter all@(x:xs) = "The first letter of " ++ all ++ " is " ++ x ++ " otherbit " ++ xs I get error: Couldn't match expected type `[Char]' with actual type `Char' In the first argument of `(++)', namely `x' In the second argument of `(++)', namely `x ++ " otherbit " ++ xs' In the second argument of `(++)', namely `" is " ++ x ++ " otherbit " ++ xs' I can use xs to print "werty" but have to use [x] to print "Q". Why is that? What does [x] mean? In the (x:xs) : just delimits each element. so x is the first element. Why can I not print by using x? Also xs is of what type? list of values? So does this mean x is an element and xs must be of type list? Confused...