[Haskell-cafe] Re: IO inside CGI

[apfelmus]

Adrian Neumann wrote:
> Now I'd like to get a new StdGen, in case no id was supplied to the script.
 >
> parse :: Maybe String-> IO StdGen
> parse (Just x) = return $ read x
> parse Nothing = getStdGen
> 
> Obviously this doesn't work because I'm trying to do IO inside CGI
> (right?). Is there some incantation I can perform to make this possible?

Abracadabra, the incantation is

   liftIO :: IO a -> CGI a

i.e.

   parse :: Maybe String-> CGI StdGen
   parse (Just x) = return $ read x
   parse Nothing  = liftIO getStdGen


Regards,
apfelmus