On Thu, 7 Feb 2008, Albert Y. C. Lai wrote:
Is it good or bad to add:
instance (MonadIO m) = MonadIO (ParsecT s u m)
I don't see any reason not to add it - it's not as if we can prevent
people lifting to IO! Good catch.
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A problem that's all in your head is still a
Probably a weird idea but could this be useful?
class (Monad m) = Stream s m t | s - t where
uncons :: s - m (m (t,s))
for example:
instance (Monad m) = Stream [t] m t where
uncons [] = return $ fail uncons []
uncons (t:ts) = return $ return (t,ts)
One small advantage is that
Is it good or bad to add:
instance (MonadIO m) = MonadIO (ParsecT s u m)
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On Sun, 3 Feb 2008, Antoine Latter wrote:
Another picky nit:
The monad transformer type is defined as such:
data ParsecT s u m a
= ParsecT { runParsecT :: State s u - m (Consumed (m (Reply s u
a))) }
with the Consumed and reply types as:
data Consumed a = Consumed a
On Feb 4, 2008 9:11 PM, Philippa Cowderoy [EMAIL PROTECTED] wrote:
It's a necessary part of how Parsec works - both the Consumed and the
Reply depend on the input stream, which is now generated from within the
base monad. The Consumed result is evaluated in advance of the Reply, so
keeping the
Another picky nit:
The monad transformer type is defined as such:
data ParsecT s u m a
= ParsecT { runParsecT :: State s u - m (Consumed (m (Reply s u a))) }
with the Consumed and reply types as:
data Consumed a = Consumed a
| Empty !a
data Reply s u a = Ok !a
I'm not a fan of parameterizing the Stream class over the monad parameter `m':
class Stream s m t | s - t where
uncons :: s - m (Maybe (t,s))
which leads to instance declarations like so:
instance Monad m = Stream [tok] m tok where
uncons [] = return $ Nothing
uncons (t:ts)
On Sat, 2 Feb 2008, Antoine Latter wrote:
I'm not a fan of parameterizing the Stream class over the monad
parameter `m':
snip
I looked through the sources and I didn't see anywhere where this
parameterization gained anything. As a proof of this I did a
mechanical re-write removing the
On Feb 2, 2008 5:28 PM, Antoine Latter [EMAIL PROTECTED] wrote:
I'm not a fan of parameterizing the Stream class over the monad parameter
`m':
class Stream s m t | s - t where
uncons :: s - m (Maybe (t,s))
which leads to instance declarations like so:
instance Monad m = Stream
On Sat, 2 Feb 2008, Antoine Latter wrote:
To expand on this point, side-effect instances of Stream don't play
nice with the backtracking in Text.Parsec.Prim.try:
import Text.Parsec
import Text.Parsec.Prim
import System.IO
import Control.Monad
type Parser a = (Stream s m Char) =
On Sat, 2008-02-02 at 20:43 -0600, Antoine Latter wrote:
On Feb 2, 2008 5:28 PM, Antoine Latter [EMAIL PROTECTED] wrote:
I'm not a fan of parameterizing the Stream class over the monad parameter
`m':
class Stream s m t | s - t where
uncons :: s - m (Maybe (t,s))
which leads to
[Now with 100% more correct darcs get URLs.]
I'm currently getting Paolo Martini's Google Summer of Code project, an
updated version of Parsec, into a releasable state, and I will be
maintaining it for at least a while.
Paolo's major additions are:
* The Parser monad has been generalized
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