[Haskell] Going nuts
chrisk at MIT.EDU
Wed Apr 20 23:32:48 EDT 2005
On Apr 20, 2005, at 10:04 PM, Alexandre Weffort Thenorio wrote:
> As usual a beginner in Haskell. Trying to write a simple program in
> shown below
> outputLine keyno key orgFile = do
> part1 <- getLeft keyno orgFile
> part2 <- getRight keyno orgFile
> total <- part1 ++ (strUpper key) ++ part2 ++ "\n"
This is just creating a new expression bound to total, not an action.
Instead of <- use let =
let total = part1 ++ (strUpper key) ++ part2 ++ "\n"
Something about Lists  also being a Monad gave a confusing error
message to you
> newHexFile <- openFileEx "newfile" (BinaryMode WriteMode)
> hPutStrLn newHexFile (orgFile!!0 ++ "\n" ++ total ++ unlines
> (drop 2
> strUpper :: String -> String
> strUpper  = ""
> --strUpper x:xs = (toUpper x):(strUpper xs)
> And I keep getting the error
> Couldn't match `[a]' against `Char'
> Expected type: [a]
> Inferred type: Char
> In the first argument of `(++)', namely `part1'
> In a 'do' expression:
> total <- part1 ++ ((strUpper key) ++ (part2 ++ "\n"))
> I have tried thousands and thousand of modifications (Originally
> getLeft and
> getRight didn't exist, the code was part of outputLine) but it keeps
> thinking that orgFile is a String when clearlly it is a [String]. Also
> I can
> get my function strUpper (Which simply puts strings to Upper case) to
> Can anybody see what is wrong here?
> Best Regards
> Haskell mailing list
> Haskell at haskell.org
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