[Haskell-beginners] Re: Monadic composition without throwing genericity under the bus?

Stephen Tetley wrote:

The parser has a type restricted return type - always a 'Hughes string' with efficient concatenation (ShowS :: String -> String) rather than some polymorphic answer (e.g a parse tree). For formatting it allows you to add text without consuming any:

inserttext :: String -> Parser inserttext str = return (showString str)

Or rewrite matched input:

rewrite :: String -> String -> Parser rewrite inp out = string inp >> return (showString out)

Or drop text, I presume this is what the place combinator does.

Its a nice technique.

Ah, nice; thanks for the explanation! Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com