Error about “type signature with no binding”

Question

I have a problem with ASCII in Haskell.

fromEnum :: Char -> Int
toEnum :: Int -> Char

offset :: Int
offset = fromEnum \'A\' - fromEnum \'a\'

toUpper ::          


        

Answer 1

fromEnum and toEnum are standart functions

please try this:

offset :: Int
offset = fromEnum 'A' - fromEnum 'a'

toUpper :: Char -> Char
toUpper ch = toEnum (fromEnum ch + offset)

Answer 2

Unless you are doing this as an exercise, you should really use toUpper from module Data.Char.

Doing this well requires to check how uppercase is defined in Unicode -- I'd rather rely on the standard library for that :)

Also, watch out because your toUpper is not idempotent: one might expect that toUpper 'A' == 'A', for instance.