[Haskell-cafe] Using Parsec with other monads
Roly Perera
roly.perera at dynamicaspects.org
Fri Nov 28 18:27:22 EST 2008
Hi,
I've spent some time writing a parser using the Parsec library and was looking
forward to being able to plug in some side-behaviour once I'd got the parser
working.
Now it seems I can't actually do that in a nice way because Parsec appears to
be "fixed" to a simple State monad.
I found this mentioned in the Cafe archives, but not much discussion. Is there
a reason Parsec wasn't implemented using the monad transformer approach? Are
there any plans to open it up? It's a nice powerful library and a natural
thing to want to do for example would be to plug in something like a Reader to
track a variable context. I guess one could abuse the State monad to achieve
the goal but that feels like the wrong tool for the job.
Any insights appreciated.
thanks,
Roly
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