haskell - About ++ to concate things -

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given following function signature:

concatthings :: (show a) => -> string -> string concatthings str2 = str2 ++ (show any)

if run concatthings "there" "hi", result be: "hi\"there\"", want "hithere".

how can still "hithere" function signature?

you wrap string in new type , provide simple show instance it:

newtype partialstring = partialstring string  instance show partialstring     show partialstring str = str

and pass in wrapped string concatthings function:

let pstr1 = partialstring str1 in concatthings pstr1 str2

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