[Haskell-beginners] Re: Monadic composition without throwing
genericity under the bus?
stephen.tetley at gmail.com
Thu Feb 4 06:25:36 EST 2010
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.
On 4 February 2010 10:46, Heinrich Apfelmus <apfelmus at quantentunnel.de> wrote:
> This looks intriguing! Can you elaborate on how this works?
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