Re: [Haskell-cafe] Propagating Parsec errors

2004-12-05 Thread Tomasz Zielonka 
On Thu, Dec 02, 2004 at 02:48:07PM +, Mark Carroll wrote:
> Is there a way in Parsec to, within a parser, throw an error generated
> by another parser? For instance, something of type
>
>   ParseError -> GenParser tok st a
>
> or whatever.

I guess no. I tried hard to find this about a month ago, but my best
approximation was something like this:

do  setPosition (errorPos err)
fail (messageString (head (errorMessages err)))

which is very, very unsatisfying.

It would be nice, if there were explicit functions in Parsec for this and
also:

instance Control.Monad.Error.MonadError ParseError (GenParser tok st) ...

Best regards,
Tomasz
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[Haskell-cafe] Propagating Parsec errors

2004-12-04 Thread Mark Carroll 
Is there a way in Parsec to, within a parser, throw an error generated 
by another parser? For instance, something of type

ParseError -> GenParser tok st a

or whatever.

-- Mark

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