Learning Haskell: confusion with reverse function and recursion -

i've started learn haskell , trying write simple function takes list of strings , reverses each string in list:

revcomp :: [string] -> [string] revcomp [] = [] revcomp [x] = [] ++ [reverse x] revcomp (x:xs) = revcomp [xs] 

when try load code in ghci, error:

couldn't match expected type `char' actual type `[char]' expected type: string actual type: [string] 

could explain , problem is? much.

the first 3 lines fine. type signature correct, second line correct, , third. (however, [] ++ [reverse x] same [reverse x].)

the fourth line, however, wrong. not not use x @ on right-hand side, have type error: revcomp [xs] calls revcomp single-element list has xs element. here, x first element of list, , xs rest of list. so, since xs has type [string], [xs] has type [[string]], revcomp takes [string]! want reverse x, , prepend result of reversing rest of list.

you can use revcomp xs reverse each string in rest of list, , (:) prepend value list (with same syntax seen in x:xs pattern used on left-hand side). should enough information fix last line. makes third line redundant, way, since [x] x:[].