Re: [Haskell-cafe] How to determine correct dependency versions for a library?
tl;dr: Breakages without upper bounds are annoying and hard to solve for package consumers. With upper bounds, and especially with sandboxes, breakage is almost non-existent. I don't see how things break with upper bounds, at least in the presence of sandboxes. If all packages involved follow the PVP, a build that worked once, will always work. Cabal 0.10 and older had problems here, but 0.14 and later will always find a solution to the dependencies if there is one (if you set max-backjumps high enough). Without sandboxes, cabal might have to reinstall a package with different dependencies, breaking other packages. It will currently warn against this. Future versions will hopefully tell you about the sandboxing features that can also be used to avoid this. In contrast, without upper bounds a packages is almost sure to fail to compile at some point. A user will then get compile errors outside his own code, somewhere in the middle of his dependency chain. Depending on his expertise, this will be either hard or impossible to fix. In particular, it is not clear that too lenient dependencies are the problem, and if it is clear, you do not know which ones. So I still see this as a tradeoff between the interests of package developers/maintainers (upper bounds give more testing/release work, and also, they want to use the latest versions) versus package users/companies (who want a build to work, but often don't care about the bleeding edge). Personnaly, I fall in both groups, and have experienced both problems. At Silk, we have (internal) packages with huge dependency chains (we depend on both happstack and snap). With cabal 0.10, this was a nightmare. Since 0.14, we've had no breakages, except from packages that do not specify upper bounds! We're fairly up-to-date with GHC versions: we're on 7.4 now, but with no immediate plans to switch to 7.6. Switching to a new GHC version is a bit of work, but we can decide when to do the work. Without upper bounds, our builds can break at any moment, and we have to fix it then and there to be able to continue working. If you do have to use the bleeding edge (or a packages uses really outdated dependencies) you can also use sandboxes to your advantage. Just 'cabal unpack' the problematic package, change the dependencies and add the resulting source package to your sandbox. This is what we do when we test out a new GHC version. We also try to contribute fixes back upstream. This is why I ask for people to specify upper bounds. They mean that packages keep working, and they prevent users from getting incomprehensible, badly timed build failures. Erik On Sat, Nov 10, 2012 at 5:16 PM, Roman Cheplyaka r...@ro-che.info wrote: * Erik Hesselink hessel...@gmail.com [2012-11-10 16:40:30+0100] On Fri, Nov 9, 2012 at 5:52 PM, Roman Cheplyaka r...@ro-che.info wrote: * Janek S. fremenz...@poczta.onet.pl [2012-11-09 17:15:26+0100] but I am aware that if the library were to be released on Hackage I would have to supply version numbers in the dependencies. The question is how to determine proper version numbers? With the current state of affairs, your best bet is not to specify any version bounds, or specify only lower ones. Upper version bounds much more often break things that fix things. I'd like to ask people not to do this. What you're doing then is moving the burden from the maintainer (who has to test with new versions and relax dependencies) to the users of the library (who will be faced with breakages when new incompatible dependencies are released). The trouble is, when things break, they break either way — so I simply propose to reduce the probability of things breaking. I know, I know, the theory is that Cabal magically installs the right versions for you. However, in practice it often can't do that due to various reasons (base libraries, package reinstalls etc.) I'm not trying to shift the burden from the maintainer — I simply know from experience that maintainers are not nearly as quick and responsible as would be required for such scheme to work, so as a *user* I'd prefer that they omit upper bounds — at least until the --ignore-constraints option is implemented. (https://github.com/haskell/cabal/issues/949) Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hard drive thrashing with modern controllers
timothyho...@seznam.cz writes: import Control.Monad foo = do forever $ writeFile filename.foo Hello world! I could be wrong, but I suspect this is unlikely to result in (hardly) any disk operations at all, as long as there is _any_ write caching in the system. will that destroy those sectors of my SSD after the rated 3000 write cycles? The SSD firmware will even this out by shuffling around the exact flash blocks that are used, so that's 3K write cycles for each block, spread out over hundreds of thousands of blocks - so your SSD should survive perhaps a billion writes in total. The reason I ask, is that I have a program here where I would like to save a set of files after every change/operation and I'm wondering if I should check if the files I'm saving have actually changed or if this will be handled by the OS... Unless the loss of a file would be crucial, I wouldn't worry about it. If/when you wear out the SSD, a replacement will probably be a trivial cost. -k ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC for mobile devices?
I found [1] a few months ago. It outputs Java bytecode, so it should work on android. Given that Android development in java is very well supported in eclipse, you might want to use haskell/frege only for the internals of your program and keep coding your interface in Java. [1] http://code.google.com/p/frege/ On 10 November 2012 01:51, Andrew Pennebaker andrew.penneba...@gmail.comwrote: I'd love to use Haskell directly for making mobiles apps. How can we make this happen, porting GHC to Android, iOS, and Windows Phone? -- Cheers, Andrew Pennebaker www.yellosoft.us ___ 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
Re: [Haskell-cafe] Motion to unify all the string data types
At Mon, 12 Nov 2012 11:21:42 +0800, John Lato wrote: Speaking as the ListLike maintainer, I'd like this too. But it's difficult to do so without sacrificing performance. In some cases, sacrificing *a lot* of performance. So they have to be class members. However, there's no reason ListLike has to remain a single monolithic class. I'd prefer an API that's split up into several classes, as was done in Edison. Then 'ListLike' itself would just be a type synonym, or possibly a small type class with the appropriate superclasses. Interesting. Are we sure that we can't convince GHC to inline the functions with enough pragmas? However this seems like a lot of work for relatively little payoff, which makes it a low priority for me. Fair enough. The community's view on newtypes is funny. On the one hand, I see all the time the claim Just use a newtype wrapper to write instances for ... (e.g. the recent suggestion of 'instance Num a = Num (a,a)'. On the other, nobody actually seems to want to use these newtype wrappers. Maybe it clutters the code? I don't know. I couldn't think of a better way to implement this functionality, patches would be gratefully accepted. Anyway, you really shouldn't use these wrappers unless you're using a ByteString to represent ASCII text. Which you shouldn't be doing anyway. If you're using a ByteString to represent a sequence of bytes, you needn't ever encounter CharString. Well newtypes are good, the problem is that either you use well accepted ones (e.g. the `Sum' and `Product' in base) or otherwise it's not worth it, because people are going to unpack them and use their owns. What I would do is simply define those instances in separate modules. Given that text and vector are both in the Haskell Platform, I wouldn't object to these instances being rolled into the main ListLike package. Any comments on this? I think it's much better, especially for Text, since if you use ListLike you are probably using it with Text (at least in my experience). Not a big deal anyway. Francesco. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Motion to unify all the string data types
At Mon, 12 Nov 2012 10:26:01 +, Francesco Mazzoli wrote: Interesting. Are we sure that we can't convince GHC to inline the functions with enough pragmas? Inline and SPECIALIZE :). Francesco. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] how to inject another source into conduit
Hello.
I have problems with writing next code (using network-conduit)
slightly simplified version:
app ad = appSource ad $$ sink
where
cMap = M.fromList [ (upload, cmdUpload), (download, cmdDownload) ]
sink = takeLine = \c - case c of Just run - run ; Nothing - return ()
cmdUpload = {- ... -} CB.sinkFile path
cmdDownload = do
{- code here -}
CB.sourceFile path $$ appSink ad -- this will not work because of
-- type error
And I'm catching cannot construct the infinite type.
I've found an example in [1], but it's not exactly solves my problem, as all
the logic is inside conduit, and it will break upload function.
[1] http://www.yesodweb.com/blog/2012/06/conduit-0-5
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Re: [Haskell-cafe] GHC for mobile devices?
Hi All, https://github.com/ghc-ios/ghc/wiki explains how to get Stephen Blackheath's GHC fork for iOS running — it's a bumpy road (cleanups are underway) but I've got Cloud Haskell, ObjectiveHaskell, LevelDB and my own libraries running wonderfully on my iPad. I just updated the wiki with a few tweaks for Mountain Lion and Xcode 4.5.2. Cheers Luke On Mon, Nov 12, 2012 at 1:41 AM, Ivan Perez ivanperezdoming...@gmail.com wrote: I found [1] a few months ago. It outputs Java bytecode, so it should work on android. Given that Android development in java is very well supported in eclipse, you might want to use haskell/frege only for the internals of your program and keep coding your interface in Java. [1] http://code.google.com/p/frege/ On 10 November 2012 01:51, Andrew Pennebaker andrew.penneba...@gmail.com wrote: I'd love to use Haskell directly for making mobiles apps. How can we make this happen, porting GHC to Android, iOS, and Windows Phone? -- Cheers, Andrew Pennebaker www.yellosoft.us ___ 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
Re: [Haskell-cafe] ANN: fixed-vector
I have a lot of one-off code where I've defined these myself. Is it
possible to e.g. define vectors in R^2 and R^3, and write the p-norm
functions only once?
Yes. it's possible.
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
import Data.Vector.Fixed as V
import Data.Vector.Fixed.Internal
-- ^^^ Needed for Fun /will be reexported from Data.Vector.Fixed
import Data.Vector.Fixed.Unboxed
First we need to define data types and instances. It's possible to use
vectors from library
data Vec2D a = Vec2D a a
type instance Dim Vec2D = S (S Z)
instance Vector Vec2D a where
inspect (Vec2D x y) (Fun f) = f x y
construct = Fun Vec2D
data Vec3D a = Vec3D a a a
type instance Dim Vec3D = S (S (S Z))
instance Vector Vec3D a where
inspect (Vec3D x y z) (Fun f) = f x y z
construct = Fun Vec3D
Now we can define generic p-norm. Maybe you had something different in
mind but still it's function which will work with any vector of fixed
length.
pNorm :: (Vector v a, Floating a) = a - v a - a
pNorm p = (** recip p) . V.sum . V.map ((** p) . abs)
We will get folloiwng in GHCi:
*Main pNorm 1 $ Vec2D 1 2 :: Double
3.0
*Main pNorm 1 $ Vec3D 1 2 3 :: Double
6.0
It's possible to avoid defining data types and use generic vectors
from library. Vec2 is synonym to Data.Vector.Fixed.Unboxed.Vec (S (S Z))
*Main pNorm 2 (vec $ con | 1 | 2 :: Vec2 Double)
2.23606797749979
At the moment their construction is a bit cumbersome
so used replicate to illustrate other vector sizes.
*Main pNorm 1 (V.replicate 1 :: Vec2 Double)
2.0
*Main pNorm 1 (V.replicate 1 :: Vec (S (S (S Z))) Double)
3.0
*Main pNorm 1 (V.replicate 1 :: Vec (S (S (S (S Z Double)
4.0
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Re: [Haskell-cafe] JavaScript (SpiderMonkey, V8, etc) embedded in GHC?
On 2012-11-10, at 2:39 PM, Simon Hengel s...@typeful.net wrote: Hi, I've looked around with no success… this surprises me actually. Has anyone embedded SpiderMonkey, V8, or any other relatively decent JavaScript interpreters in GHC (using the FFI)? I just started something [1]. Cheers, Simon [1] https://github.com/sol/v8 Nice! Thanks! I'll have a go with it today or tomorrow. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strange behavior with listArray
On Mon, Nov 12, 2012 at 08:36:49AM +0100, Bas van Dijk wrote: On 12 November 2012 04:50, Alex Stangl a...@stangl.us wrote: I'm stymied trying to figure out why the program below blows up with loop when I use f 0 If you replace the a!0 in f by its value 0, f is equivalent to: f k = if k 0 then f 0 else 0 : f 1 Do you see the loop now? I realize it loops/recurses, just like h does, or any instance of building lazy infinite data structures. It works fine when you only extract a finite number of elements from the infinite structure. It's not clear why that is not happening here, as if there is a failure of laziness. f 0 should effectively yield [0, 0, ...], correct? Maybe you meant f to be: f k = if k 0 then f (a!k) else 0 : f 1 Actually it was that way in the original program. I switched it to 0 the process of trying to distill it down to a simplest test. Either way yield the same result, loop. If you take the array reference out, this code works fine, as it obviously should. But with the array reference intact, it appears listArray isn't accessing the list lazily enough. Thanks, Alex ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strange behavior with listArray
On Montag, 12. November 2012, 08:36:49, Bas van Dijk wrote: On 12 November 2012 04:50, Alex Stangl a...@stangl.us wrote: I'm stymied trying to figure out why the program below blows up with loop when I use f 0 If you replace the a!0 in f by its value 0, f is equivalent to: f k = if k 0 then f 0 else 0 : f 1 Do you see the loop now? I see no loop in that, and ghci doesn't either: Prelude let f :: Int - [Int]; f k = if k 0 then f 0 else 0 : f 1 Prelude take 5 $ f 1 [0,0,0,0,0] and if you use (f 0) instead of (f (a!0)) there, it works. Maybe you meant f to be: f k = if k 0 then f (a!k) else 0 : f 1 Loops too. The problem, Alex, is that f k = if k 0 then f (a!0) else 0 : f 1 is strict, it needs to know the value of (a!0) to decide which branch to take. But the construction of the array a needs to know how long the list (0 : f 0) is (well, if it's at least four elements long) before it can return the array. So there the cat eats its own tail, f needs to know (a part of) a before it can proceed, but a needs to know more of f to return than it does. g and h are not strict, they simply let the construction write thunks into the array elements, and those can then later be evaluated after the construction of a has returned. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strange behavior with listArray
On 12 November 2012 14:52, Daniel Fischer daniel.is.fisc...@googlemail.com wrote: I see no loop in that, and ghci doesn't either: Oops you're right of course. Bas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to determine correct dependency versions for a library?
On Mon, Nov 12, 2012 at 1:06 AM, Erik Hesselink hessel...@gmail.com wrote: tl;dr: Breakages without upper bounds are annoying and hard to solve for package consumers. With upper bounds, and especially with sandboxes, breakage is almost non-existent. I don't see how things break with upper bounds, at least in the presence of sandboxes. If all packages involved follow the PVP, a build that worked once, will always work. Cabal 0.10 and older had problems here, but 0.14 and later will always find a solution to the dependencies if there is one (if you set max-backjumps high enough). The breakage people are talking about with regards to upper bounds is that every time a new version of a dependency comes out, packages with upper bounds can't compile with it, even if they would without the upper bound. For example, the version number of base is bumped with almost every GHC release, yet almost no packages would actually break to the changes that caused that major version number to go up. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] how to inject another source into conduit
I don't think there's enough information in the snippet you've given to
determine what the problem is. And in general, it's a good idea to include
the actual error message from the compiler.
On Mon, Nov 12, 2012 at 5:02 AM, Alexander V Vershilov
alexander.vershi...@gmail.com wrote:
Hello.
I have problems with writing next code (using network-conduit)
slightly simplified version:
app ad = appSource ad $$ sink
where
cMap = M.fromList [ (upload, cmdUpload), (download, cmdDownload)
]
sink = takeLine = \c - case c of Just run - run ; Nothing -
return ()
cmdUpload = {- ... -} CB.sinkFile path
cmdDownload = do
{- code here -}
CB.sourceFile path $$ appSink ad -- this will not work because
of
-- type error
And I'm catching cannot construct the infinite type.
I've found an example in [1], but it's not exactly solves my problem, as
all
the logic is inside conduit, and it will break upload function.
[1] http://www.yesodweb.com/blog/2012/06/conduit-0-5
--
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[Haskell-cafe] Quickcheck
Hi, Trying to find some good docs on QuickCheck, if anyone has one ? Been scanning what I can find, but a question. What would be the best way to generate two different/distinct integers ? Use arbitrary ( if so do you have an example ) or a conditional on the property. Though I read the later can reduce passing test count. Thanks Graham ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to determine correct dependency versions for a library?
On Mon, Nov 12, 2012 at 5:13 PM, Johan Tibell johan.tib...@gmail.comwrote: On Mon, Nov 12, 2012 at 1:06 AM, Erik Hesselink hessel...@gmail.comwrote: tl;dr: Breakages without upper bounds are annoying and hard to solve for package consumers. With upper bounds, and especially with sandboxes, breakage is almost non-existent. I don't see how things break with upper bounds, at least in the presence of sandboxes. If all packages involved follow the PVP, a build that worked once, will always work. Cabal 0.10 and older had problems here, but 0.14 and later will always find a solution to the dependencies if there is one (if you set max-backjumps high enough). The breakage people are talking about with regards to upper bounds is that every time a new version of a dependency comes out, packages with upper bounds can't compile with it, even if they would without the upper bound. For example, the version number of base is bumped with almost every GHC release, yet almost no packages would actually break to the changes that caused that major version number to go up. Yes, this is why I talk about living on the bleeding edge, and shifting the burden from package maintainers to package users. And I believe the last base changes included a change to 'catch' which would have broken a lot of packages. The Num changes also caused a lot of code changes, and there were probably more I don't remember. Erik ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Strange behavior with listArray
On Mon, Nov 12, 2012 at 02:52:28PM +0100, Daniel Fischer wrote: The problem, Alex, is that f k = if k 0 then f (a!0) else 0 : f 1 is strict, it needs to know the value of (a!0) to decide which branch to take. But the construction of the array a needs to know how long the list (0 : f 0) is (well, if it's at least four elements long) before it can return the array. So there the cat eats its own tail, f needs to know (a part of) a before it can proceed, but a needs to know more of f to return than it does. g and h are not strict, they simply let the construction write thunks into the array elements, and those can then later be evaluated after the construction of a has returned. Thanks for the thoughtful, detailed answer. If you have a function like f that has conditional logic, and accesses earlier elements in the list stream, can this be memoized? It appears that constructing an array via array or listArray won't work, nor does an IntMap. I can layer my list index [1] on top to speed up the list access, but this isn't as good as using an array. Thanks, Alex [1] http://github.com/astangl/list-index ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Hard drive thrashing with modern controllers
On Mon, Nov 12, 2012 at 4:21 AM, Ketil Malde ke...@malde.org wrote: timothyho...@seznam.cz writes: import Control.Monad foo = do forever $ writeFile filename.foo Hello world! I could be wrong, but I suspect this is unlikely to result in (hardly) any disk operations at all, as long as there is _any_ write caching in the system. Maybe no data blocks, but the metadata will be updated. -- brandon s allbery kf8nh sine nomine associates allber...@gmail.com ballb...@sinenomine.net unix/linux, openafs, kerberos, infrastructure http://sinenomine.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Quickcheck
On Mon, Nov 12, 2012 at 07:21:06PM +, gra...@fatlazycat.com wrote: Hi, Trying to find some good docs on QuickCheck, if anyone has one ? Been scanning what I can find, but a question. What would be the best way to generate two different/distinct integers ? I would use Quickcheck's implication operator here: quickCheck $ \x y - x /= (y :: Int) == ... Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] curl package broken in Windows
Hi, the curl binding certainly needs some love---if anyone has the time to fix it up and maintain it, help would be most appreciated. There is a repo for it over here: https://github.com/GaloisInc/curl which is the most up-to date version I know of, but since the last commit there seems to be from 4 years ago, I'm not going to bet that there aren't any additional fixes floating around. (cc-ing Don, who is listed as the maintainer, but I'm not sure if he has time to deal with curl right now) -Iavor On Sun, Nov 11, 2012 at 3:34 PM, Erik de Castro Lopo mle...@mega-nerd.comwrote: Kevin Cantu wrote: With the curl package on Hackage, I merely need an SSL enabled version of libcurl, and every Linux distro I've tried this on has several variations of such a package. (You have a choice of OpenSSL or GNUTLS, for example.) I tried the CURL bindings on Linux some time ago and I personally found the thing pretty much un-usable. The API was incomplete, inconsistent and way too close to the C API. However, I have had much better luck with Michael Snoyman's http-conduit package, which being pure Haskell (ie no C) should be much easier to install on windows. Erik -- -- Erik de Castro Lopo http://www.mega-nerd.com/ ___ 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
Re: [Haskell-cafe] curl package broken in Windows
On Mon, Nov 12, 2012 at 01:48:23PM -0800, Iavor Diatchki wrote: Hi, the curl binding certainly needs some love---if anyone has the time to fix it up and maintain it, help would be most appreciated. There is a repo for it over here: https://github.com/GaloisInc/curl which is the most up-to date version I know of, but since the last commit there seems to be from 4 years ago, I'm not going to bet that there aren't any additional fixes floating around. (cc-ing Don, who is listed as the maintainer, but I'm not sure if he has time to deal with curl right now) I've tried to contact Don multiple times over the past month with offers of whatever help I can give, but I heard nothing back. I didn't know about the github repo (it's not listed on the hackage page), so thanks a lot for that info, I'll try to send some merge requests and file bugs (there is a least one critical bug w.r.t. SSL usage on Linux and another small-impact bug with cookie jars usage). iustin, who uses curl and _really_ wants to see it improved ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Quickcheck
On Mon, Nov 12, 2012 at 10:14:30PM +0100, Simon Hengel wrote: On Mon, Nov 12, 2012 at 07:21:06PM +, gra...@fatlazycat.com wrote: Hi, Trying to find some good docs on QuickCheck, if anyone has one ? Been scanning what I can find, but a question. What would be the best way to generate two different/distinct integers ? I would use Quickcheck's implication operator here: quickCheck $ \x y - x /= (y :: Int) == ... That's good, but it only eliminates test cases after they have been generated. A slightly better (IMHO) version is to generate correct values in the first place: prop_Test :: Property prop_Test = forAll (arbitrary::Gen Int) $ \x - forAll (arbitrary `suchThat` (/= x)) $ \y - … regards, iustin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] curl package broken in Windows
On Mon, Nov 12, 2012 at 10:57:25PM +0100, Iustin Pop wrote: On Mon, Nov 12, 2012 at 01:48:23PM -0800, Iavor Diatchki wrote: Hi, the curl binding certainly needs some love---if anyone has the time to fix it up and maintain it, help would be most appreciated. There is a repo for it over here: https://github.com/GaloisInc/curl which is the most up-to date version I know of, but since the last commit there seems to be from 4 years ago, I'm not going to bet that there aren't any additional fixes floating around. (cc-ing Don, who is listed as the maintainer, but I'm not sure if he has time to deal with curl right now) I've tried to contact Don multiple times over the past month with offers of whatever help I can give, but I heard nothing back. I didn't know about the github repo (it's not listed on the hackage page), so thanks a lot for that info, I'll try to send some merge requests and file bugs (there is a least one critical bug w.r.t. SSL usage on Linux and another small-impact bug with cookie jars usage). Hmm, checking again, the github repo is at version 1.3.5 (April 2009), whereas hackage is at version 1.3.7 (uploaded in May 2011). Still hunting for a correct upstream project page or tracker… regards, iustin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Reminder and Forward: Wednesday 14 November 2012 NYHUG Inaugural Meetup: Ozgun Ataman on Practical Data Processing and Gershom Bazerman on Putting Cloud Haskell to Work
Below is a version of the announcement sent to the haskell-cafe and the haskell mailing lists by Gershom Bazerman on 9 October 2012. oo--JS. blockquote what=official New York Haskell Users Group announcement rsvp=Yes, see below. more=http://en.wikipedia.org/wiki/Haskell_%28programming_language%29 [page was last modified on 11 November 2012 at 00:56] http://www.haskell.org/haskellwiki/Haskell http://www.reddit.com/r/haskell http://www.aosabook.org/en/ghc.html http://en.wikipedia.org/wiki/Type_inference [page was last modified on 15 September 2012 at 15:37] http://en.wikipedia.org/wiki/Hindley%E2%80%93Milner [page was last modified on 9 October 2012 at 17:40] http://www.users.waitrose.com/~hindley/ http://www.cs.ru.nl/~henk/ http://www.usingz.com/ http://en.wikipedia.org/wiki/Curry-Howard [page was last modified on 14 September 2012 at 22:01] http://www.paultaylor.eu/stable/prot.pdf ftp://ftp.cs.cmu.edu/usr/rwh/www/home/courses/logic/www/handouts/curry-howard.pdf http://www.students.science.uu.nl/~3448584/TypeSystems.pdf http://www.math.ias.edu/~vladimir/Site3/Univalent_Foundations_files/2011_Goteborg.pdf http://math.andrej.com/2012/11/08/how-to-implement-dependent-type-theory-i/ http://math.andrej.com/2012/11/11/how-to-implement-dependent-type-theory-ii/ http://math.andrej.com/2012/10/03/am-i-a-constructive-mathematician/; exclamation-of-old-lisper-upon-first-seeing-curry-howard-theorem: But this is clearly wrong! Look I have a function string-length which has type String-Int, but 'String-Int' is not a theorem of any usual intuitionistic propositional logic. insight-of-newbie-coming-to-haskell-from-lisp: Lisp's now buried background would require, if a student of Lisp were to ask for an outline of this background, a book of perhaps a hundred pages. Haskell, and more generally, all the New Crazy Types programming systems, would require three hundred pages. edits=some adventitious markup and some blank space removed Subject: Wednesday 14 November, NY Haskell Inaugural Meetup: Practical Data Processing _and_ Putting Cloud Haskell to Work Date: Fri, 12 Oct 2012 18:05:02 -0400 From: Gershom B gersh...@gmail.com To:l...@lispnyc.org == What: New York Haskell Users Group Meeting When: Wednesday, November 14, 2012 7 PM - 9 PM Where: Pivotal Labs, 841 Broadway, 8th floor (Just south of Union Square) http://maps.google.com/maps?q=841+Broadway,+New+York RSVP: http://www.meetup.com/NY-Haskell/ == * 7 PM - Practical Data Processing With Haskell * 8 PM - Putting Cloud Haskell to Work for Distributed Computing -- 7 PM - Practical Data Processing With Haskell: Ozgun Ataman will give an introductory talk on Haskell, diving right in with how you can start using Haskell for practical data manipulation tasks today. You'll be introduced to a typical setup for Haskell development and given a demonstration of how a common data format (CSV, JSON, etc.) can be parsed, processed and finally output using Haskell. The talk will include a small actual Haskell program to be modified live and some commentary around using Haskell in practical applications. 8 PM - Putting Cloud Haskell to Work for Distributed Computing: Gershom Bazerman will give an overview of the new distributed-process library that implements Cloud Haskell, providing computation across heterogeneous nodes through a message passing interface. He will discuss what this new tool provides out of the box, and what you'll have to bring to the table. The talk will include some code samples using the new library, as well as some experience about what it's like to use Haskell for distributed computing in the real world. Speaker Biographies: Ozgun Ataman is the founder of Soostone, a management consulting and analytics company built on Haskell. He is the author of many open-source Haskell libraries, and is a contributor to the Snap web framework. Gershom Bazerman is a developer at SP Capital IQ. He is most well known in the Haskell community as the author of the JMacro library for programmatic generation of JavaScript, and for one well-received April fools joke. -- We're kicking off the New York Haskell Users Group with two great talks, one for people just getting started and one for those with some experience already. Both should be accessible and enjoyable no matter how much (or little) you already know. Food and refreshments will be provided, courtesy of
Re: [Haskell-cafe] curl package broken in Windows
Hi, Ok, there were only minor differences between the repo and the version on hackage so I imported the changes into the repo, which should now be the same as version 1.3.7 on hackage. Please feel free to submit merge requestsall the folks I know who worked on this originally are busy with other stuff, so we really need someone who's using the library to help. Thanks! -Iavor On Mon, Nov 12, 2012 at 2:06 PM, Iustin Pop iu...@k1024.org wrote: On Mon, Nov 12, 2012 at 10:57:25PM +0100, Iustin Pop wrote: On Mon, Nov 12, 2012 at 01:48:23PM -0800, Iavor Diatchki wrote: Hi, the curl binding certainly needs some love---if anyone has the time to fix it up and maintain it, help would be most appreciated. There is a repo for it over here: https://github.com/GaloisInc/curl which is the most up-to date version I know of, but since the last commit there seems to be from 4 years ago, I'm not going to bet that there aren't any additional fixes floating around. (cc-ing Don, who is listed as the maintainer, but I'm not sure if he has time to deal with curl right now) I've tried to contact Don multiple times over the past month with offers of whatever help I can give, but I heard nothing back. I didn't know about the github repo (it's not listed on the hackage page), so thanks a lot for that info, I'll try to send some merge requests and file bugs (there is a least one critical bug w.r.t. SSL usage on Linux and another small-impact bug with cookie jars usage). Hmm, checking again, the github repo is at version 1.3.5 (April 2009), whereas hackage is at version 1.3.7 (uploaded in May 2011). Still hunting for a correct upstream project page or tracker… regards, iustin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to determine correct dependency versions for a library?
Especially in the case of base, not sure how upper bounds help at all: If incompatible, you break with or without upper bounds. Actually getting errors related to Num instances is more informative IMO. If compatible, you just get false negatives and errors. In either case cabal can't install an older base to make the build work, so what do you gain? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] curl package broken in Windows
On 11/12/12 17:43, Iavor Diatchki wrote: Hi, Ok, there were only minor differences between the repo and the version on hackage so I imported the changes into the repo, which should now be the same as version 1.3.7 on hackage. Please feel free to submit merge requestsall the folks I know who worked on this originally are busy with other stuff, so we really need someone who's using the library to help. I reported this a while ago, and Iustin gave an awesome explanation of the problem: http://haskell.1045720.n5.nabble.com/Network-Curl-cookie-jar-madness-td5716344.html I've since switched to http-conduit for that project but it would be nice to have curl working anyway because it requires less thinking. If someone's going to maintain it, then consider this a bug report! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: fixed-vector
On 11/12/12 01:57, Carter Schonwald wrote: Michael, I think that calls for a type-class! (though I imagine theres a slicker way of writing it) I'm already using typeclasses, but there's still a bit of boilerplate. I could probably think of something more clever myself, but like I said, these are just one-off experiments, and I'm lazy. So I'm hoping fixed-vector will do it for me! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ANN: fixed-vector
On 11/12/12 07:05, Aleksey Khudyakov wrote:
I have a lot of one-off code where I've defined these myself. Is it
possible to e.g. define vectors in R^2 and R^3, and write the p-norm
functions only once?
Yes. it's possible.
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
import Data.Vector.Fixed as V
import Data.Vector.Fixed.Internal
-- ^^^ Needed for Fun /will be reexported from Data.Vector.Fixed
import Data.Vector.Fixed.Unboxed
First we need to define data types and instances. It's possible to use
vectors from library
...
Thanks, this looks like exactly what I need. I'll try to replace my R^2
and R^3 implementations the next time I do my homework before the last
minute.
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Re: [Haskell-cafe] JavaScript (SpiderMonkey, V8, etc) embedded in GHC?
Out of curiosity: wouldn't it make more sense to focus on the other direction (calling Haskell from V8)? Roughly like: I guess it really depends what you are after. If you want to cabalize existing JS libs, then I think bindings to V8 make perfect sense ;) Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
