[Haskell-beginners] Error Message when trying to solve alphametic(SEND + MORE = MONEY)

[Matthew Moppett]

Hi Sok Ha.

expr    = show send ++ "+" ++ show more ++ "=" show money



On Sun, Jan 26, 2014 at 7:16 PM, Sok Ha Chang <shaegis at gmail.com> wrote:
> Hi.
> I’m new to Haskell.
> Use Haskell Platform on MacBook Air.
> $ ghc --version
> The Glorious Glasgow Haskell Compilation System, version 7.6.3
>
> I’m try to solve alphametic.
> SEND + MORE = MONEY
>
> Here is code…
> ----------------------------------------------------------------------------------------------------------
> import Data.List
>
> decryp :: [Int] -> String -> String
> decryp (s:e:n:d:o:r:y:[]) a =
>         if send + more == money then expr:a else a
>         where
>                 send    = s * 1000 + e * 100 + n * 10 + d
>                 more    = 1000 + o * 100 + r * 10 + e
>                 money   = 10000 + o * 1000 + n * 100 + e * 10 + y
>                 expr    = show send ++ "+" ++ show more ++ "=" show money
>
> decrypSolver :: [String]
> decrypSolver =
>         foldr decryp [] (permutations 7 [0, 2, 3, 4, 5, 6, 7, 8, 9])
> ----------------------------------------------------------------------------------------------------------
>
> Error Messages is
> ./decrypSolver.hs: line 10, column 60:
>   Couldn't match expected type `(a0 -> String) -> Int -> [Char]'
>               with actual type `[Char]'
>   The function `"="' is applied to two arguments,
>   but its type `[Char]' has none
>   In the second argument of `(++)', namely `"=" show money'
>   In the second argument of `(++)', namely
>     `show more ++ "=" show money’
> ----------------------------------------------------------------------------------------------------------
>
> How can I fix this?
>
> Thank you.
>
> Sincerely, S. Chang
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