[Haskell-cafe] Re: do/if/then/else confusion

[David Carter]

David Carter wrote:

> Another newbie question, but I can't seem to find any answers on the 
> web...


Just figured it out myself ... I need a "do" after the "else", of 
course. (But I still think the error message is less than helpful!).

Sorry for the bandwidth

David

>
> Can someone tell me what's wrong with this?
>
> import qualified System.Posix.Directory as PD
>
> readdirAll :: PD.DirStream -> IO [String]
> readdirAll d =
>   do dir <- PD.readDirStream d
>      if dir == ""
>        then return []
>        else rest <- readdirAll d
>             return (dir:rest)
>
> Compiling with GHC 6.6.1 gives me the not-very-useful message "Parse 
> error in pattern", pointing to the "i" of "if". I've tried all kinds 
> of alternative indentations (including indenting the "else" more), 
> bracketings etc, but nothing helps.
>
> Thanks
>
> David
>
>



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