[Haskell-beginners] Basic Parsec question

Antoine Latter aslatter at gmail.com
Wed Apr 1 00:34:16 EDT 2009

2009/3/31 Zachary Turner <divisortheory at gmail.com>:
> Hi,
> I downloaded the package lispparser to, well, parse lisp code.  I really
> have absolutely no idea what I'm doing though.  I can look at the source of
> the module and see that it's exporting a single data type called LispVal and
> a single function called parseExpr, so somehow I should be able to pass an
> arbitrary block of lisp code into this function and get back a LispVal.  But
> for the life of me I can't figure out how.  I've looked at the documentation
> but I get even more confused because it links me to the Parsec documentation
> which is probably way over my head.  Basically I just want a simple
> function:
> parse :: String -> LispVal
> parse expr = ???
> presumably by making some use of the exported 'thing' (since I'm not really
> sure how to interpret its type)
> parseExpr :: Parser LispVal
> Thanks for any help

You should be able to use the function "parse" from the parsec package like so:

> parse parseExp "name of source for error reporting" "(some lisp expression")

The function "parse" returns a value of type (Either ParseError a),
where in this case the type-var 'a' wil be a LispVal.

Does that help?


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