Question

Given the following function signature:

concatThings :: (Show a) => a -> String -> String
concatThings any str2 = str2 ++ (show any)

If run concatThings "there" "hi", then result will be: "hi\"there\"", but what I want is just "hithere".

How can I still get “hithere” with this function signature?

Answer 1

You could wrap the string in a new type and provide a simple Show instance for it:

newtype PartialString = PartialString String

instance Show PartialString where
    show PartialString str = str

and then pass in a wrapped string to the concatThings function:

let pstr1 = PartialString str1 in concatThings pstr1 str2