On Wed, Feb 06, 2013 at 01:09:51PM +0100, Michele Tartara wrote:
> In order to fetch precise information about the status of the VMs running in
> Xen, we need to analyze the output of the "xm list --long" command.
>
> This commit adds the parser to do that, and its tests.
Separate comment from the backtracking issue:
> +-- | A parser for parsing generic config files written in the (LISP-like)
> +-- format that is the output of the @xm list --long@ command.
> +-- This parser only takes care of the syntactic parse, but does not care
> +-- about the semantics.
> +lispConfigParser :: Parser LispConfig
> +lispConfigParser =
> + A.skipSpace *>
> + ( listConfigP
> + <|> doubleP
> + <|> stringP
> + )
> + <* A.skipSpace
> + where listConfigP =
> + (A.char '(' *> lispConfigParser `AC.manyTill` A.char ')')
> + >>= pure . LCList
> + doubleP = A.double >>= pure . LCDouble
> + stringP =
> + A.takeWhile1 (
> + \c -> (not . isSpace) c
> + && (c /= ')')
> + && (c /= '(')
> + ) >>= (pure . LCString . unpack )
You're mixing here Applicative and Monad operations (>>= pure . …). It
would be IMHO cleaner to use just the Applicative interface:
listConfigP = LCList <$> (A.char …)
doubleP = LCDouble <$> A.double
stringP = LCString . unpack <$> …
thanks,
iustin
