Re: [Haskell] ANN: Yi 0.6.3
On Mon, 28 Mar 2011 14:40:21 -0500, Jeff Wheeler wrote: > On Mon, Mar 28, 2011 at 7:33 AM, Edward Amsden wrote: > >> * mention alex in the cabal file (I don't remember the syntax but there is > >> a way to specify tools needed to build). > > build-tools: alex > > > > in the library/executable section > > Oh, my bad. I removed this because alex is included in the Platform, > so it seemed like it'd always be available. I'll add it back. > > I originally pulled pointedlist from Yi, but since switched from > data-accessor to fclabels per suggestions by a few people. I also put > the repo on github, it's on the yi-editor account page. Do we want to > do the same switch on Yi? (I'll readily admit that I don't really know > the advantages of data-accessor vs. fclabels.) I would suggest going to fclabels for Yi itself as well. > I don't know about rose-zipper, but I'll look at that. I think releasing the constraint is enough for rose-zipper. -- Nicolas Pouillard http://nicolaspouillard.fr ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] ANN: Yi 0.6.3
On Fri, 25 Mar 2011 01:23:46 -0500, Jeff Wheeler wrote: > Hi all, > > I'm very excited to announce the first release of Yi since last > summer. It is relatively light on new features, but it finally should > compile nicely on friendly machines. This means, for the most part, > machines with the latest Haskell Platform installed. (Windows, > unfortunately, has not been tested all that much. See details below, > though, for install info.) Great work. Pardon me complaining again but it would be much more easier to integrate into ArchLinux if the following changes where made: * mention alex in the cabal file (I don't remember the syntax but there is a way to specify tools needed to build). * depends on latest version of dependencies: pointedlist, rose-zipper Cheers, -- Nicolas Pouillard http://nicolaspouillard.fr ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell] Re: ANNOUNCE: countable-1.0
On Mon, 06 Sep 2010 03:46:18 -0700, Ashley Yakeley wrote: > countable: Countable, Searchable, Finite, Empty classes. > >class Countable, for countable types >class AtLeastOneCountable, for countable types that have at least one > value >class InfiniteCountable, for infinite countable types >class Searchable, for types that can be searched over >class Finite, for finite types >class Empty, for empty types >data Nothing, an empty type > > Also includes these orphan instances: > >instance (Searchable a,Eq b) => Eq (a -> b) >instance (Finite a) => Foldable ((->) a) >instance (Finite a) => Traversable ((->) a) >instance (Show a,Finite a,Show b) => Show (a -> b) Could you put these instances in a dedicated module? In the same vein I would like to have a newtype wrapper over functions were intention is to be used extensionally. Nice package BTW! -- Nicolas Pouillard http://nicolaspouillard.fr ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell] Re: [Haskell-cafe] ANN: hsparql, a SPARQL query generator/DSL and client
Excerpts from Jeff Wheeler's message of Thu Jul 09 00:27:51 +0200 2009: > I'm excited to announce the first version of hsparql. HSparql makes it > easy to query SPARQL-compliant servers using a relatively intuitive DSL > and very simple client. I've looked at your DSL and it looks really neat. While reading I was wondering if GADTs could help having an even nicer query language. -- Nicolas Pouillard http://nicolaspouillard.fr ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] [ANN] Safe Lazy IO in Haskell
Excerpts from Jason Dusek's message of Sun May 17 15:45:25 +0200 2009: > From the documentation: > > " LI could be a strict monad and a strict applicative functor. > However it is not a lazy monad nor a lazy applicative > functor as required Haskell. Hopefully it is a lazy > (pointed) functor at least. The type I would need for bind is this one: (>>=) :: NFData sa => LI sa -> (sa -> LI b) -> LI b And because of the NFData constraint this type bind is less general than the required one. BTW this operator is exported as (!>>=) by System.IO.Lazy.Input.Extra. By using the rmonad we could add this NFData constraint, but that's not like having a Monad instance directly. Best regards, -- Nicolas Pouillard ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell] [ANN] Safe Lazy IO in Haskell
System.IO", and strict 'IORef''s.
One can now introduce a function in lines of 'mapHandleContents':
> withHandleContents :: NFData sa => Handle -> (String -> SIO sa) -> IO sa
> withHandleContents h f = do
> s <- hGetContents h
> SIO.run (f s) `finally` hClose h
One can then rewrite 'lowerText' as follow:
> lowerText = withHandleContents stdin (SIO.putStr . map toLower)
Until there one can deal quite nicely with single input, many outputs
processing. Currently the only requirement is to delimit a scope where
the resource will be used to return a strict value.
Dealing with multiple inputs will lead us to our final design of lazy
inputs.
== Introducing 'LI', Lazy Inputs ==
We first introduce a type for these lazy inputs namely 'LI'.
This type is abstract and we will progressively introduce functions
to build, combine and run them.
The 'LI' type is a pointed functor, but not necessarily a monad nor
an applicative functor.
Therefore one exports the 'pure' function as 'pureLI'. Building primitives
allow to read files or handles:
> LI.pureLI :: a -> LI a
> LI.hGetContents :: Handle -> LI String
> LI.getContents :: LI String
> LI.readFile :: FilePath -> LI String
> LI.getChanContents :: Chan a -> LI [a]
Being a functor is important: it allows to wholly transform the underlying
input lazily using standard functions about lists for instance:
> length <$> LI.readFile "foo"
> words <$> LI.readFile "foo"
Extracting a final value of a lazy input ('LI' type) is a matter of using:
> LI.run :: (NFData sa) => LI sa -> IO sa
Or
> LI.run' :: (NFData sa) => LI (SIO a) -> IO sa
One can therefore re-write our examples using lazy inputs:
> -- embedded printing
> countWords = LI.run' (SIO.print . length . words <$> LI.getContents)
> -- external printing
> maxLineLen = print =<< LI.run (maximum . map length . lines <$>
> LI.getContents)
> lowerText = LI.run' (SIO.putStr . map toLower <$> LI.getContents)
== Combining inputs ==
Finally we come to managing multiple inputs. To get both laziness and
precise resource management we will provide dedicated combinators.
The first one is as simple as appending.
> LI.append :: NFData sa => LI [sa] -> LI [sa] -> LI [sa]
This one produces a single stream out that sequences the two given streams.
It also sequences the usage of resources: the first resource is closed and
then the second one is opened.
Note that this combinator is still quite general since one can process each
input beforehand:
> -- one can drop parts of the inputs
> (take 100 <$> i1) `LI.append` (drop 100 <$> i2)
> -- one can tag each input to know where they come from
> Left <$> i1 `LI.append` Right <$> i2
The second one is 'LI.zipWith' which opens the two resources and joins the items
into a single stream. Again, since 'LI' is a functor one can join not only
characters but also words, lines, chunks... A problem with zipping is that it
stops on the shorter input (loosing a part of the other), hopefully one can
prolongate them:
> zipMaybesWith :: (NFData sa, NFData sb) -> (Maybe sa -> Maybe sb -> c) -> LI
> [sa] -> LI [sb] -> LI [c]
> zipMaybesWith f xs ys =
> map (uncurry f) . takeWhile someJust <$> zip (prolongate <$> xs)
> (prolongate <$> ys)
> where someJust (Nothing, Nothing) = False
> someJust _ = True
> prolongate :: [a] -> [Maybe a]
> prolongate zs = map Just zs ++ repeat Nothing
The last one is 'LI.interleave':
> LI.interleave :: (NFData sa) -> LI [sa] -> LI [sa] -> LI [sa]
This function is currently left biased, moreover each resource is closed as soon
as we reach its end. However since the inputs are mixed up together one
generally
prefers a tagged version trivially build upon this one:
> interleaveEither :: (NFData sa, NFData sb) => LI [sa] -> LI [sb] -> LI
> [Either sa sb]
> interleaveEither a b = interleave (map Left <$> a) (map Right <$> b)
Here are some final programs that scale well with the number of files.
> -- number of words in the given files
> main = print =<< LI.run . fmap (length . words) . LI.concat . map LI.readFile
> =<< getArgs
> -- almost the same thing but counts words independently in each file
> main = print
> =<< LI.run . fmap sum . LI.sequence . map (fmap (length . words) .
> LI.readFile)
> =<< getArgs
> -- prints to stdout swap-cased concatenation of all input files
> main = LI.run' . (fmap (SIO.putStr . fmap swapCase) . LI.concat . map
> LI.readFile) =<< getArgs
> where swapCase c | isUpper c = toLower c
>| otherwise = toUpper c
> -- sums character code points of inputs
> main = print =<< LI.run . fmap (sum . map (toInteger . ord)) . LI.concat .
> map LI.readFile =<< getArgs
Our solution is from now widely available as an Hackage package named
"safe-lazy-io" [4].
We hope you will freely enjoy using Lazy/IO again!
As usual, criticisms, comments, and help are expected!
Finally, I would like to thank Benoit Montagu and Francois Pottier for helping
me out to polish this work!
[1]: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/safe-lazy-io
[2]: http://okmij.org/ftp/Streams.html
[3]: http://www.haskell.org/pipermail/haskell/2009-March/021064.html
[4]: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/strict-io
--
Nicolas Pouillard
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Re: [Haskell] ANNOUNCE: htags-1.0
Excerpts from David Sankel's message of Mon Nov 03 19:25:23 +0100 2008: > http://hackage.haskell.org/cgi-bin/hackage-scripts/package/htags > > htags is a tag file generator to enable extra functionality in editors > like vim. It expands upon hasktags by using a full Haskell 98 parser > and options for recursion. Hi, I've just tried to install it and the build fails here (GHC 6.8.3) $ cabal update $ cabal install htags ──(Mon,Nov03)─┘ Resolving dependencies... Downloading htags-1.0... Configuring htags-1.0... Preprocessing executables for htags-1.0... Building htags-1.0... src/htags.hs:8:7: Could not find module `GenTags': Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: htags-1.0 failed during the building phase. The exception was: exit: ExitFailure 1 Best regards, -- Nicolas Pouillard aka Ertai ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
