Re: [Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
On Tue, Jun 4, 2013 at 10:15 PM, Ivan Lazar Miljenovic wrote: > > Isn't this done automatically when you have files with the .hsc extension? > No, it is not. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Why isn't hsc2hs functionality provided by ghc?
I was wondering today, why hasn't hsc2hs been merged with ghc so that
it would be possible to add a
{-# LANGUAGE ForeignFunctionInterface #-}
at the top of a source file and then load it with ghci or compile it,
without the intermediate step of calling hsc2hs? This would be exactly
like the CPP extension. I don't have to call cpp manually. All I have
to do is to add {-# LANGUAGE CPP #-} and then ghc will take care of
the rest. This would also mean that there would be no need to have a
separate file extension. Surely I must not be the first person to have
that thought, so there must be a good reason why this hasn't happen
yet, but what is it?
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Re: [Haskell-cafe] parsec: parserFail & multiple error messages
On Thu, Aug 9, 2012 at 3:59 AM, Christian Maeder wrote: > The error message can be improved in your examples by using "count 5" > instead of "many1". Yes, I know. That's what I ended up doing. But this is an ad hoc solution. I think parsec should offer a more general solution. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] parsec: parserFail & multiple error messages
Inserting a character into the stream can be expensive if for example the stream is a ByteString. I tried the following crazy solution and it seems that it works: succeed :: Parser () succeed = mkPT $ \st -> return $ Consumed $ return $ Ok () st $ unknownError st succeed is a parser that always succeeds without really consuming any input but it also resets the error state. I really have no understating of how mkPT works. Can someone tell me if this is a bad idea? On Wed, Aug 8, 2012 at 4:09 PM, Nick Vanderweit wrote: > I found a similar question asked in June 2009 on the haskell-beginners > archives, titled "Clearing Parsec error messages." A hack that was proposed > (http://www.haskell.org/pipermail/beginners/2009-June/001809.html) was to > insert a dummy character into the stream, consume it, and then fail. Still, > I'd like to see if there is a cleaner way to modify the error state in the > Parsec monad. > > > NIck > > On Wednesday, August 08, 2012 03:24:31 PM silly wrote: >> I am trying to create a parsec parser that parses an integer and then >> checks if that integer has the right size. If not, it generates an >> error. >> I tried the following: >> >> 8<--- >> import Text.Parsec >> import Text.Parsec.String >> >> integer :: Parser Int >> integer = do s <- many1 digit >> let n = read s >> if n > 65535 then >> parserFail "integer overflow" >> else >> return n >> 8<--- >> >> The problem is that when I try this >> >> parse integer "" "7" >> >> I get the following error: >> >> Left (line 1, column 6): >> unexpected end of input >> expecting digit >> integer overflow >> >> ie there are three error messages but I only want the last one. Is >> there something I can do about this? >> >> ___ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe > > ___ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] parsec: parserFail & multiple error messages
I am trying to create a parsec parser that parses an integer and then checks if that integer has the right size. If not, it generates an error. I tried the following: 8<--- import Text.Parsec import Text.Parsec.String integer :: Parser Int integer = do s <- many1 digit let n = read s if n > 65535 then parserFail "integer overflow" else return n 8<--- The problem is that when I try this parse integer "" "7" I get the following error: Left (line 1, column 6): unexpected end of input expecting digit integer overflow ie there are three error messages but I only want the last one. Is there something I can do about this? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
