[Haskell-cafe] ghci can't load file whose name contains non-ASCII chars?
I must be making some obvious mistake here, but I'm not seeing it. The file name contains O-umlaut, and the OS handles it fine, but ghci does not like it (although it accepts umlauts in the contents of the file (UTF-8) e.g., as a module name) $ cat fÖÖbar.hs main = print $ product [1..100] $ ghci fÖÖbar.hs GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. no location info: can't find file: f??bar.hs Failed, modules loaded: none. this is on a standard ubuntu install (11.10 and 11.04) with $ locale LANG=en_US.UTF-8 LANGUAGE= LC_CTYPE=en_US.UTF-8 ... $ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.4.1 $ uname -a Linux octopus 3.0.0-16-generic #29-Ubuntu SMP Tue Feb 14 12:48:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci can't load file whose name contains non-ASCII chars?
On 28 March 2012 18:44, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: I must be making some obvious mistake here, but I'm not seeing it. The file name contains O-umlaut, and the OS handles it fine, but ghci does not like it (although it accepts umlauts in the contents of the file (UTF-8) e.g., as a module name) $ cat fÖÖbar.hs main = print $ product [1..100] $ ghci fÖÖbar.hs GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. no location info: can't find file: f??bar.hs Failed, modules loaded: none. this is on a standard ubuntu install (11.10 and 11.04) with $ locale LANG=en_US.UTF-8 LANGUAGE= LC_CTYPE=en_US.UTF-8 ... $ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.4.1 $ uname -a Linux octopus 3.0.0-16-generic #29-Ubuntu SMP Tue Feb 14 12:48:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux I'm able to duplicate this (also on a 64bit Linux install with 7.4.1). ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com http://IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Regarding Haskell FFI
On 27/03/2012 08:56, rajendra prasad wrote: Hi, I am trying to load the DLL(Wrapper.dll) in my code(Main.hs). When I am placing the dll in local directory, I am able to load it through following command: ghci Main.hs -L. -lWrapper But, I am not able to load it if I am putting it in some other directory(../../bin). I used the following command: ghci Main.hs -L../../bin/ -lWrapper I doubt I am not using the correct way to specify the path of dll in the command. Please correct me if I am wrong. What version of GHC is this? We fixed some bugs in that area recently. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Regarding Haskell FFI
Hi, I am using GHC version 7.0.4. Thanks, Rajendra On Wed, Mar 28, 2012 at 2:09 PM, Simon Marlow marlo...@gmail.com wrote: On 27/03/2012 08:56, rajendra prasad wrote: Hi, I am trying to load the DLL(Wrapper.dll) in my code(Main.hs). When I am placing the dll in local directory, I am able to load it through following command: ghci Main.hs -L. -lWrapper But, I am not able to load it if I am putting it in some other directory(../../bin). I used the following command: ghci Main.hs -L../../bin/ -lWrapper I doubt I am not using the correct way to specify the path of dll in the command. Please correct me if I am wrong. What version of GHC is this? We fixed some bugs in that area recently. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Regarding Haskell FFI
I think the fix eventually made its way into 7.4.1. This is the patch: http://hackage.haskell.org/trac/ghc/changeset/d146fdbbf8941a8344f0ec300e79dbeabc08d1ea Cheers, Simon On 28/03/2012 09:57, rajendra prasad wrote: Hi, I am using GHC version 7.0.4. Thanks, Rajendra On Wed, Mar 28, 2012 at 2:09 PM, Simon Marlow marlo...@gmail.com mailto:marlo...@gmail.com wrote: On 27/03/2012 08:56, rajendra prasad wrote: Hi, I am trying to load the DLL(Wrapper.dll) in my code(Main.hs). When I am placing the dll in local directory, I am able to load it through following command: ghci Main.hs -L. -lWrapper But, I am not able to load it if I am putting it in some other directory(../../bin). I used the following command: ghci Main.hs -L../../bin/ -lWrapper I doubt I am not using the correct way to specify the path of dll in the command. Please correct me if I am wrong. What version of GHC is this? We fixed some bugs in that area recently. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Fail-back monad
Sorry, the text example again without HTML formatting:
test= runBackT $ do
lift $ print will not return back here
liftBackPoint $ print will return here
n2 - lift $ getLine
lift $ print second input
n3 - lift $ getLine
if n3 == back
then fail
else lift $ print $ n2++n3
I wrote a blog entry about this :
http://haskell-web.blogspot.com.es/2012/03/failback-monad.html
2012/3/28 Alberto G. Corona agocor...@gmail.com:
Hi Haskellers.
In my package MFlow [1] I program an entire web navigation in a
single procedure. That happened in the good-old WASH web application
framework.
The problem is the back button in the Browser.
To go back in the code to the previous interactions when the data
input does not match the expected because the user pressed the back
button one or more times, i came across this Monad specimen,: that
solves the problem.
data FailBack a = BackPoint a -- will go back to this point
| NoBack a . -- Normal outcome
| GoBack -- exception:: must
go to the last backPoint
newtype BackT m a = BackT { runBackT :: m (FailBack a ) }
-- this monad nas a loop
instance Monad m = Monad (BackT m) where
fail _ = BackT $ return GoBack
return x = BackT . return $ NoBack x
x = f = BackT $ loop
where
loop = do
v - runBackT x
case v of
NoBack y - runBackT (f y) -- business as usual
BackPoint y - do
z - runBackT (f y)
case z of
GoBack - loop -- if x was a backpoint,
then redirects the flow to this backpoint
other - return other
GoBack - return GoBack --propagate the signal back
This monad does not perform exploration of alternatives as is the
case of MonadPlus instances. It does not perform the kind of
backtracking of nondeterministic three navigations in the Prolog
style. It just go back to the last point where the computation can
restart again in a sequence of actions.
In this example:
liftBackPoint f= BackT $ f = \x - return $ BackPoint x
test= runBackT $ do
lift $ print will not return back here
liftBackPoint $ print will return here
n2 lt;- lift $ getLine
lift $ print second input
n3 lt;- lift $ getLine
if n3 == back
then fail
else lift $ print $ n2++n3
Whenever the second input is back The procedure will go back to
where liftBackPoint is. Otherwise, it will return the concatenation of
the two inputs. If the underlying monad is an instance of MonadState,
it can transport the state that caused the failure to the backpoint.
Are there something similar? May it be functionally equivalent to
something simpler or with more grounds?
I looked at some exception monads out there, but they did not seems
to share the same idea
[1]
http://haskell-web.blogspot.com.es/2012/02/web-application-server-with-stateful.html
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Re: [Haskell-cafe] Regarding Haskell FFI
Thank you very much for the quick reply. Regards, Rajendra On Wed, Mar 28, 2012 at 2:35 PM, Simon Marlow marlo...@gmail.com wrote: I think the fix eventually made its way into 7.4.1. This is the patch: http://hackage.haskell.org/**trac/ghc/changeset/** d146fdbbf8941a8344f0ec300e79db**eabc08d1eahttp://hackage.haskell.org/trac/ghc/changeset/d146fdbbf8941a8344f0ec300e79dbeabc08d1ea Cheers, Simon On 28/03/2012 09:57, rajendra prasad wrote: Hi, I am using GHC version 7.0.4. Thanks, Rajendra On Wed, Mar 28, 2012 at 2:09 PM, Simon Marlow marlo...@gmail.com mailto:marlo...@gmail.com wrote: On 27/03/2012 08:56, rajendra prasad wrote: Hi, I am trying to load the DLL(Wrapper.dll) in my code(Main.hs). When I am placing the dll in local directory, I am able to load it through following command: ghci Main.hs -L. -lWrapper But, I am not able to load it if I am putting it in some other directory(../../bin). I used the following command: ghci Main.hs -L../../bin/ -lWrapper I doubt I am not using the correct way to specify the path of dll in the command. Please correct me if I am wrong. What version of GHC is this? We fixed some bugs in that area recently. Cheers, Simon ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GSoC project idea: haskell-type-exts
See ticket here: http://hackage.haskell.org/trac/summer-of-code/ticket/1620 == What? == The haskell-src-exts library (HSE) is very popular for manipulating Haskell source code in a wide range of scenarios, such as (syntactic) preprocessors (e.g. hsx), syntax highlighting, refactoring and code inspection (e.g. hlint), etc. A commonly sought feature, that would enable a multitude of new and improved scenarios, is the ability to type-check the code, and annotate the AST with type information. Type-driven refactoring, type-aware code inspection, type-based preprocessing, ... Lots of pure awesomeness lies in that direction. Sadly, HSE has no type-checking abilities. For those who seek such, we are forced to point in the direction of the dark cave that is the GHC API. While GHC is an utterly awesome compiler, there are several reasons why this is not an ideal situation. First, GHC was designed and built for optimization, which means that even the early stages of the compilation pipeline contain features that cater to later optimization, but that are (at best) unnecessary for a front-end tool. Second, the API into GHC internals is defined as an afterthought. Some good work has been done to make it somewhat palatable, but it remains a fact that GHC's primary purpose is not to be a library for integration in tools, and this shows. Overall, depending on GHC when all you want is front-end capabilities like parsing and typechecking, is really like using the proverbial sledge hammer. Also, at the meta level, GHC deserves competition. Right now GHC is de facto the only implementation of Haskell, and as such it more or less defines the progress of Haskell. Too often this leads to overly pragmatic choices, which lead to inconsistencies and headaches for tool programmers. Having a separate, stand-alone front end library would help set higher standards. So - what we need is a type checker that works on the HSE AST: haskell-type-exts! == How? == I now hear you think: This is too much, an enormous project, surely it can't be done as a GSoC project? Sure it can! By walking in the footsteps of giants, and following GHC's approach. This can be achieved by closely observing the documentation provided by [1] and [2], with a bit of [3] thrown into the mix. I already have a basic library that provides most of the core framework necessary to cover extensions, but at this time it's mostly just scaffolding. It needs a lot of love, to provide cover for all the various available extensions, but I'm confident it can be done satisfactorily as a GSoC project. Still, it would be reasonable to modularize the task. Certain features are more crucial than others to support, simply because they have a more profound impact on the overall type-checking. Higher-rank types, GADTs and type families (and fundeps) are likely the most important ones to get right. There are also some design issues to get right (e.g. using pure substitution vs efficient mutable variables). I (Niklas Broberg) am more than willing to mentor this project. == Further reading: == [1] S. Peyton Jones, D. Vytiniotis, S. Weirich, and M. Shields. Practical type inference for arbitrary-rank types. [2] D. Vytiniotis, S. Peyton Jones, T. Schrijvers, M. Sulzmann. OutsideIn(X) – Modular type inference with local assumptions [3] M. P. Jones. Typing Haskell in Haskell ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Mathematics and Statistics libraries
There is the plot[1] library which provides for updateable plots from GHCi REPL and has a gnuplot-like interface. I wrote it for this very reason, a mathematics/statistics development environment. It uses Data.Vector.Storable, which provides for compatability with both statistics and hmatrix packages (as well as hstatistics). Looks very interesting. I'll try it out. I think talking about data frames is a bit pointless unless we specify what is data frame. Basically there are two representations of tabular data structure: array of tuples or tuple of arrays. If you want first go for Data.Vector.Vector YourData. If you want second you'll probably end up with some HList-like data structure to hold arrays. Matrices from hmatrix are easily converted to rows or columns of Data.Vector.Storable and can be sliced and otherwise manipulated. That's why I said that homogenous data frame is simple. But if you want to have columns which hold values with different type they lo longer a matrix and thing become way more interesting. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci can't load file whose name contains non-ASCII chars?
On Wed, Mar 28, 2012 at 11:49 AM, Ivan Lazar Miljenovic ivan.miljeno...@gmail.com wrote: On 28 March 2012 18:44, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: I must be making some obvious mistake here, but I'm not seeing it. The file name contains O-umlaut, and the OS handles it fine, but ghci does not like it (although it accepts umlauts in the contents of the file (UTF-8) e.g., as a module name) I looks like GHC correctly decodes command line parameters and then truncates them to 8-bit. $ ghci ффф command line: Could not find module `DDD' fromEnum 'ф' `mod` 256 == fromEnum 'D' True ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Google Summer of Code - Lock-free data structures
Hi again, I just submitted my proposal on the GSoC website. You can find it here: http://www.google-melange.com/gsoc/proposal/review/google/gsoc2012/florianhartwig/1 I would be very grateful if someone could read over it and tell me if it makes sense and if/how it could be improved. Cheers, Florian ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ANNOUNCE: haskell-src-exts-1.13.0
Fellow Haskelleers, I'm pleased to announce the release of haskell-src-exts-1.13.0! * On hackage: http://hackage.haskell.org/package/haskell-src-exts * Via cabal: cabal install haskell-src-exts * Darcs repo: http://code.haskell.org/haskell-src-exts It's been a *very short* while since the last update before this, and another (smallish) major release it is. Sorry about that (especially to Neil who was quick to update). The main update of this release is to add support for DoAndIfThenElse, which means haskell-src-exts at long last is compliant with Haskell2010. This is also the cause for the backwards-incompatible change: default parse mode is now to use Haskell2010 mode. In particular this means that NPlusKPatterns is no longer recognized by default. No old code using haskell-src-exts should fail to compile (unless really unlucky with clashing imports from L.H.E.Extension), but it may now fail to work on some Haskell98-compliant source files. Changelog: 1.12.0 -- 1.13.0 === * Add extensions DoAndIfThenElse and NPlusKPatterns to Language.Haskell.Exts.Extensions. * DoAndIfThenElse is now supported, at long last, making HSE compatible with Haskell2010 * Introduce haskell98 and haskell2010 extension groups, exported from Language.Haskell.Exts.Extensions. * Backwards-incompatible change: default parse mode is now to use haskell2010, which means the following features are recognized by default: DoAndIfThenElse, PatternGuards, ForeignFunctionInterface, EmptyDataDecls. NPlusKPatterns is no longer recognized by default. Cheers, /Niklas ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Fail-back monad
Maybe this is a version of William Harrison's DebugT monad with rollback, listed in his periodic table of effects? http://www.cs.missouri.edu/~harrisonwl/Presentations/UIUCFM05.ppt I've never seen a definition of the monad itself... http://www.haskell.org/pipermail/beginners/2010-January/003371.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Fail-back monad
Hi Stephen: It could be: It performs a rollback indeed. I guess that this monad can be used in something similar to nonblocking (multilevel) transactions. if GoBack is changed to Goback String, and a trace string is added to each NoBack step, then each NoBack step could sum the traces of all the previous steps. The when GoBack condition is reached, it can transport back the entire trace of the failed execution. to the BackPoint 2012/3/28 Stephen Tetley stephen.tet...@gmail.com: Maybe this is a version of William Harrison's DebugT monad with rollback, listed in his periodic table of effects? http://www.cs.missouri.edu/~harrisonwl/Presentations/UIUCFM05.ppt I've never seen a definition of the monad itself... http://www.haskell.org/pipermail/beginners/2010-January/003371.html ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] for = flip map
Good: we have mapM, and we have forM ( = flip mapM ) . Sure this is just a convenience, and indeed forM xs $ \ x - do ... is quite handy, especially if xs is really small, and ... is some larger expression. Bad: we have map, but we are missing: for ( = flip map ) . The function is very convenient, for the same reasons as above. I can't remember how often I typed for = flip map in a source file. I never put this definition in a module either, since the import statement would be longer than the definition. So, I'm all for for . In Data.List? In the Prelude? (Should put it right next to map.) - J.W. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] for = flip map
Similar proposal here: http://www.reddit.com/r/haskell/comments/qy990/suggestion_for_flip_map/ It seems generally favorable. Might as well generalize it though and have flip fmap. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] for = flip map
Doesn't for already exist, in Data.Traversable? Except that for = flip traverse. http://www.haskell.org/hoogle/?hoogle=for Cheers, -Matthew On Wed, Mar 28, 2012 at 3:58 PM, Johannes Waldmann waldm...@imn.htwk-leipzig.de wrote: Good: we have mapM, and we have forM ( = flip mapM ) . Sure this is just a convenience, and indeed forM xs $ \ x - do ... is quite handy, especially if xs is really small, and ... is some larger expression. Bad: we have map, but we are missing: for ( = flip map ) . The function is very convenient, for the same reasons as above. I can't remember how often I typed for = flip map in a source file. I never put this definition in a module either, since the import statement would be longer than the definition. So, I'm all for for . In Data.List? In the Prelude? (Should put it right next to map.) - J.W. ___ 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] for = flip map
On 28 March 2012 22:05, Matthew Steele mdste...@alum.mit.edu wrote: Doesn't for already exist, in Data.Traversable? Except that for = flip traverse. Traverse doesn't fit the type of fmap, it demands an extra type constructor: traverse :: (Traversable t,Applicative f) = (a - f b) - t a - f (t b) fmap :: Functor f = (a - b) - f a - f b Note the (a - f b) instead of (a - b). E.g. fmap :: (a - b) - [a] - [b] can't be expressed with traverse, you can only get this far: traverse :: (a - [b]) - [a] - [[b]] Unless I'm missing something. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] winhugs interrupts
On windows I have long used hugs under cygwin, but hugs doesn't get along well with cygwin's latest terminal emulator. So I switched to winhugs. Small problem that looms big: how do you interrupt an interminable expression evaluation in winhugs? Doug ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANNOUNCE: haskell-src-exts-1.13.0
On 28 March 2012 21:05, Jurriaan Hage j.h...@uu.nl wrote: Our first year students will be very unhappy to hear this. Wait, what? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] [Haskell] ANNOUNCE: haskell-src-exts-1.13.0
On Wed, Mar 28, 2012 at 5:52 PM, dag.odenh...@gmail.com dag.odenh...@gmail.com wrote: Wait, what? Perhaps they were assigned the task of updating haskell-src-exts code to support Haskell2010? =) -- Felipe. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Can't install snap (problem with syb)
I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then tried to install snap. I get: $ cabal install snap Resolving dependencies... Downloading syb-0.3.6... command line: cannot satisfy -package Cabal-1.14.0: Cabal-1.14.0-0338b6f52e6e6a56054371a110e1d79e is unusable due to missing or recursive dependencies: directory-1.1.0.2-8957520ced1fb19160c3a6126dcccfaa process-1.1.0.1-91185c964ab744c1f3cbca1863d2ba45 (use -v for more information) cabal: Error: some packages failed to install: aeson-0.6.0.0 depends on syb-0.3.6 which failed to install. snap-0.8.0.2 depends on syb-0.3.6 which failed to install. syb-0.3.6 failed during the configure step. The exception was: ExitFailure 1 Any ideas? Mike. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] for = flip map
Think of traverse as a mapA, as it's just like Data.Traversable.mapM, but with the Applicative class constraint instead of the Monad one. I've always wondered why it isn't called this way, sequenceM equivalent for Applicatives is sequenceA for instance. Le 28 mars 2012 22:19, Christopher Done chrisd...@googlemail.com a écrit : On 28 March 2012 22:05, Matthew Steele mdste...@alum.mit.edu wrote: Doesn't for already exist, in Data.Traversable? Except that for = flip traverse. Traverse doesn't fit the type of fmap, it demands an extra type constructor: traverse :: (Traversable t,Applicative f) = (a - f b) - t a - f (t b) fmap :: Functor f = (a - b) - f a - f b Note the (a - f b) instead of (a - b). E.g. fmap :: (a - b) - [a] - [b] can't be expressed with traverse, you can only get this far: traverse :: (a - [b]) - [a] - [[b]] Unless I'm missing something. ___ 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] Can't install snap (problem with syb)
It may come from the version of GHC you're using (Cabal version is fixed for one specific GHC version). Which one is it? Le 28 mars 2012 23:05, Michael Iles michael.i...@ca.ibm.com a écrit : I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then tried to install snap. I get: $ cabal install snap Resolving dependencies... Downloading syb-0.3.6... command line: cannot satisfy -package Cabal-1.14.0: Cabal-1.14.0-0338b6f52e6e6a56054371a110e1d79e is unusable due to missing or recursive dependencies: directory-1.1.0.2-8957520ced1fb19160c3a6126dcccfaa process-1.1.0.1-91185c964ab744c1f3cbca1863d2ba45 (use -v for more information) cabal: Error: some packages failed to install: aeson-0.6.0.0 depends on syb-0.3.6 which failed to install. snap-0.8.0.2 depends on syb-0.3.6 which failed to install. syb-0.3.6 failed during the configure step. The exception was: ExitFailure 1 Any ideas? Mike. ___ 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] Can't install snap (problem with syb)
I'm using ghc 7.4.1 (from the Ubuntu Precise repository). Don't know if this is relevant but ghc-pkg list tells me that I have: /var/lib/ghc/package.conf.d Cabal-1.14.0 directory-1.1.0.2 process-1.1.0.1 ... Mike. From: Yves Parès yves.pa...@gmail.com To: Michael Iles/Ottawa/IBM@IBMCA Cc: haskell-cafe@haskell.org Date: 03/28/2012 05:13 PM Subject:Re: [Haskell-cafe] Can't install snap (problem with syb) Sent by:limestr...@gmail.com It may come from the version of GHC you're using (Cabal version is fixed for one specific GHC version). Which one is it? Le 28 mars 2012 23:05, Michael Iles michael.i...@ca.ibm.com a écrit : I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then tried to install snap. I get: $ cabal install snap Resolving dependencies... Downloading syb-0.3.6... command line: cannot satisfy -package Cabal-1.14.0: Cabal-1.14.0-0338b6f52e6e6a56054371a110e1d79e is unusable due to missing or recursive dependencies: directory-1.1.0.2-8957520ced1fb19160c3a6126dcccfaa process-1.1.0.1-91185c964ab744c1f3cbca1863d2ba45 (use -v for more information) cabal: Error: some packages failed to install: aeson-0.6.0.0 depends on syb-0.3.6 which failed to install. snap-0.8.0.2 depends on syb-0.3.6 which failed to install. syb-0.3.6 failed during the configure step. The exception was: ExitFailure 1 Any ideas? Mike. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe inline: graycol.gif___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] for = flip map
I would very much like to see a standard function for flip map along these lines. I think it would make a lot of code more readable. Like the OP, I use for in my own code. It's unfortunate that Data.Traversable takes the name with another type. Two options would be to (a) reuse the name in Data.List and force people to qualify as necessary, or (b) choose another name for flip map. Regarding other possible names: forall is a keyword and forAll is used by QuickCheck. One possibility would be foreach. Ezra On Wed, Mar 28, 2012, at 10:19 PM, Christopher Done wrote: On 28 March 2012 22:05, Matthew Steele mdste...@alum.mit.edu wrote: Doesn't for already exist, in Data.Traversable? Except that for = flip traverse. Traverse doesn't fit the type of fmap, it demands an extra type constructor: traverse :: (Traversable t,Applicative f) = (a - f b) - t a - f (t b) fmap :: Functor f = (a - b) - f a - f b Note the (a - f b) instead of (a - b). E.g. fmap :: (a - b) - [a] - [b] can't be expressed with traverse, you can only get this far: traverse :: (a - [b]) - [a] - [[b]] Unless I'm missing something. ___ 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] Can't install snap (problem with syb)
On Wed, Mar 28, 2012 at 17:05, Michael Iles michael.i...@ca.ibm.com wrote: I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then tried to install snap. I get: Did you also remove ~/.ghc? Libraries are actually installed and registered there, not under ~/.cabal. Although this shouldn't be a problem if any Cabal-installed libraries were for a different version of ghc, it's safest to remove both. -- brandon s allbery allber...@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can't install snap (problem with syb)
Did you install the haskell-platform package? What is the output of ghc-pkg check? On Wed, Mar 28, 2012 at 5:30 PM, Brandon Allbery allber...@gmail.comwrote: On Wed, Mar 28, 2012 at 17:05, Michael Iles michael.i...@ca.ibm.comwrote: I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then tried to install snap. I get: Did you also remove ~/.ghc? Libraries are actually installed and registered there, not under ~/.cabal. Although this shouldn't be a problem if any Cabal-installed libraries were for a different version of ghc, it's safest to remove both. -- brandon s allbery allber...@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms ___ 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] Can't install snap (problem with syb)
Hey that fixed it! (Removing ~/.ghc.) Thanks! Mike. From: Brandon Allbery allber...@gmail.com To: Michael Iles/Ottawa/IBM@IBMCA Cc: haskell-cafe@haskell.org Date: 03/28/2012 06:32 PM Subject:Re: [Haskell-cafe] Can't install snap (problem with syb) On Wed, Mar 28, 2012 at 17:05, Michael Iles michael.i...@ca.ibm.com wrote: I uninstalled ghc, removed my ~/.cabal directory, reinstalled ghc, then tried to install snap. I get: Did you also remove ~/.ghc? Libraries are actually installed and registered there, not under ~/.cabal. Although this shouldn't be a problem if any Cabal-installed libraries were for a different version of ghc, it's safest to remove both. -- brandon s allbery allber...@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms inline: graycol.gif___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Can't install snap (problem with syb)
On 12-03-28 06:30 PM, Brandon Allbery wrote: Did you also remove ~/.ghc? Libraries are actually installed and registered there, not under ~/.cabal. Reality is less simplistic than that. .ghc has library metadata. .cabal has library files. See my http://www.vex.net/~trebla/haskell/sicp.xhtml and verify, verify, verify. Since GHC simply trusts its metadata (and not re-scan library files to re-discover libraries), metadata dominates. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] for = flip map
On Mar 28, 2012, at 4:19 PM, Christopher Done wrote: On 28 March 2012 22:05, Matthew Steele mdste...@alum.mit.edu wrote: Doesn't for already exist, in Data.Traversable? Except that for = flip traverse. Traverse doesn't fit the type of fmap, it demands an extra type constructor: traverse :: (Traversable t,Applicative f) = (a - f b) - t a - f (t b) fmap :: Functor f = (a - b) - f a - f b Note the (a - f b) instead of (a - b). E.g. fmap :: (a - b) - [a] - [b] can't be expressed with traverse, you can only get this far: traverse :: (a - [b]) - [a] - [[b]] Unless I'm missing something. That right; I was simply pointing out that the name 'for' is already taken by an existing base function. Things might be more consistant if 'traverse' and 'for' were instead called 'mapA' and 'forA' (by analogy with 'mapM' and 'forM'). Then one could add 'for = flip map' to base without conflict. But for some reason, that's not the case. Cheers, -Matthew ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] adding the elements of two lists
Date: Tue, 27 Mar 2012 11:03:54 +1300 From: Richard O'Keefe o...@cs.otago.ac.nz Subject: Re: [Haskell-cafe] adding the elements of two lists To: jerzy.karczmarc...@unicaen.fr Cc: haskell-cafe@haskell.org And *that* is why I stopped trying to define instance Num t = Num [t]. If I KNEW that the length of the lists is ... fixed ... then the type wasn't *really* [t], but some abstract type that happened to be implemented as [t], and that abstract type deserved a newtype name of its own. Naming the type - makes the author's intent clearer to readers - lets the compiler check it's used consistently - lets you have instances that don't match instances for other abstract types that happen to have the same implementation - provides a natural place to document the purpose of the type - gives you a way to enforce the intended restrictions all for zero run-time overhead. Quite taken by this manifesto for high style and morality, I resolved to do right by some old code, of which I had been quite proud: www.cs.dartmouth.edu/~doug/powser.html. Sadly, the exercise took some bloom off the rose. What the code gained in honesty and safety, it lost in beauty and readability. Here's the contrast, seen in overloading arithmetic to handle addition and multiplication of power series. - without newtype toSeries f = f : repeat 0 -- coerce scalar to series instance Num a = Num [a] where (f:fs) + (g:gs) = f+g : fs+gs (f:fs') * gs@(g:gs') = f*g : fs'*gs + (toSeries f)*gs' - with newtype newtype Num a = PS a = PS [a] deriving (Show, Eq) fromPS (PS fs) = fs -- extract list toPS f = PS (f : repeat 0) -- coerce scalar to series instance Num a = Num (PS a) where (PS (f:fs)) + (PS (g:gs)) = PS (f+g : fs+gs) (PS (f:fs)) * gPS@(PS (g:gs)) = PS $ f*g : fromPS ((PS fs)*gPS + (toPS f)*(PS gs)) The code suffers a pox of PS. When one goes on to introduce efficiencies and generalize to handle finite series (polynomials), it only gets worse. One unpleasant technical problem: the deriving clause is almost useless--one can't print or detect equality of infinite objects. For output one must apply something like (take 10 . fromPS). Yet this modest package would likely pose problems if it were combined with others in a grander suite for automated mathematics. What to do? I think I might write the package without newtype, and then wrap it in PS for export in hopes of exploiting the advantages of both styles. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: Issue 220
Welcome to issue 220 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of March 18 to 24, 2012. Quotes of the Week * shachaf: Type classes are a scary story that you tell new Haskellers so they can go to sleep at night. * acowley: Parametric polymorphism is the inspiring story you tell them to get them riled up and raring to go. It's like Braveheart for programmers. * monochrom: the purpose of types is to ban more programs * rostayob: I was a type constructor, then I took an arrow in the kind * shachaf: @let otherfoolish = not otherwise * flebron: Monoidal objects in the monoidal category of endofunctors on a category. I took a small detour through tensor products to understand monoidal categories better, with one example of such a product. mauke: I have no idea what you just said * weexplat: starts a proposal to replace launchMissiles with atomicDestroyBiosphere * monochrom: rumour: SPJ will write a thick book A New Science of Kind * JonathanShapiro: [on abandoning BitC] And I *still* don't believe in monads. :-) Top Reddit Stories * Starting the Mezzo Haskell Book Domain: yesodweb.com, Score: 58, Comments: 28 On Reddit: [1] http://goo.gl/pOSlR Original: [2] http://goo.gl/ecy4O * First patches for iPhone cross compiler against GHC head Domain: haskell.org, Score: 55, Comments: 27 On Reddit: [3] http://goo.gl/OOAai Original: [4] http://goo.gl/p7C3L * Retrospective thoughts on BitC by its author, and why type classes didn't work for him Domain: coyotos.org, Score: 44, Comments: 22 On Reddit: [5] http://goo.gl/0sL80 Original: [6] http://goo.gl/5pCp2 * Google Summer of Code 2012 - Haskell.org is participating Domain: haskell.org, Score: 42, Comments: 11 On Reddit: [7] http://goo.gl/9EwzD Original: [8] http://goo.gl/XqcUJ * Conduits vs. Pipes. Using Void as an Input or Output type can reduce the number of concepts (source, sink, conduit) from 3 to 1 (pipe). Domain: twanvl.nl, Score: 34, Comments: 50 On Reddit: [9] http://goo.gl/bc8RB Original: [10] http://goo.gl/eb7oz * Announcing conduit 0.3 Domain: yesodweb.com, Score: 33, Comments: 9 On Reddit: [11] http://goo.gl/JrgV0 Original: [12] http://goo.gl/OsDl7 * Haskell for embedded domain-specific languages (Functional Programming eXchange 2012) Domain: skillsmatter.com, Score: 31, Comments: 4 On Reddit: [13] http://goo.gl/pSREX Original: [14] http://goo.gl/1azVh * Domain theory course Domain: cs.nott.ac.uk, Score: 31, Comments: 5 On Reddit: [15] http://goo.gl/5VHyG Original: [16] http://goo.gl/o2pRC * ANNOUNCE: options, an easy-to-use command-line option parser Domain: self.haskell, Score: 29, Comments: 21 On Reddit: [17] http://goo.gl/s6ktw Original: [18] http://goo.gl/s6ktw * A Case Study in Creating Rich Internet Apps in Haskell (Silk at FP eXchange 2012) Domain: skillsmatter.com, Score: 22, Comments: 18 On Reddit: [19] http://goo.gl/ZdtDq Original: [20] http://goo.gl/Ta2HQ * It just occurred to me that (lift .) defines a functor... Domain: self.haskell, Score: 22, Comments: 15 On Reddit: [21] http://goo.gl/GMzPt Original: [22] http://goo.gl/GMzPt Top StackOverflow Questions * Haskell platform: nested functions and optimization votes: 15, answers: 2 Read on SO: [23] http://goo.gl/nreIr * newtype with RankNTypes votes: 14, answers: 2 Read on SO: [24] http://goo.gl/UT9DV * Pattern Matching - Prolog Vs Haskell votes: 13, answers: 4 Read on SO: [25] http://goo.gl/3hZV1 * How does this definition of ArrowLoop.loop work? votes: 13, answers: 2 Read on SO: [26] http://goo.gl/ocSCM * Data.Set : does it always know best? votes: 12, answers: 2 Read on SO: [27] http://goo.gl/NUjkB * Building a histogram with haskell, many times slower than with python votes: 11, answers: 3 Read on SO: [28] http://goo.gl/kbh5i * What is the scope of let when used without in? votes: 11, answers: 2 Read on SO: [29] http://goo.gl/bNwna * Strange half to even rounding in different languages [closed] votes: 11, answers: 3 Read on SO: [30] http://goo.gl/lnPch * Practical reasons for Сhurch Encoding votes: 10, answers: 1 Read on SO: [31] http://goo.gl/xYoef * Can the FFI deal with arrays? If so, how? votes: 9, answers: 3 Read on SO: [32] http://goo.gl/d4R3H Until next time, Daniel Santa Cruz References 1. http://www.yesodweb.com/blog/2012/03/start-mezzo-haskell 2. http://www.reddit.com/r/haskell/comments/r9xdq/starting_the_mezzo_haskell_book/ 3.
Re: [Haskell-cafe] adding the elements of two lists
On 29/03/2012, at 3:08 PM, Doug McIlroy wrote: - without newtype toSeries f = f : repeat 0 -- coerce scalar to series instance Num a = Num [a] where (f:fs) + (g:gs) = f+g : fs+gs (f:fs') * gs@(g:gs') = f*g : fs'*gs + (toSeries f)*gs' - with newtype newtype Num a = PS a = PS [a] deriving (Show, Eq) fromPS (PS fs) = fs -- extract list toPS f = PS (f : repeat 0) -- coerce scalar to series instance Num a = Num (PS a) where (PS (f:fs)) + (PS (g:gs)) = PS (f+g : fs+gs) (PS (f:fs)) * gPS@(PS (g:gs)) = PS $ f*g : fromPS ((PS fs)*gPS + (toPS f)*(PS gs)) Try it again. newtype PS a = PS [a] deriving (Eq, Show) u f (PS x)= PS $ map f x b f (PS x) (PS y) = PS $ zipWith f x y to_ps x = PS (x : repeat 0) ps_product (f:fs) (g:gs) = whatever instance Num a = Num (PS a) where (+) = b (+) (-) = b (-) (*) = b ps_product negate = u negate abs = u abs signum = u signum fromInteger = to_ps . fromInteger I've avoided defining ps_product because I'm not sure what it is supposed to do: the definition doesn't look commutative. The code suffers a pox of PS. But it doesn't *need* to. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Google Summer of Code - Lock-free data structures
GHC already has a CAS primitive on MutVar#, it just needs to be extended to MutableArray# and MutableByteArray# (at all of the bit-widths the CAS instruction would support, e.g. see readWordXxArray# in http://www.haskell.org/ghc/docs/latest/html/libraries/ghc-prim-0.2.0.0/GHC-Prim.html). The implementation should be almost identical to casMutVar#. In particular I think you need: casMutArray# :: MutableArray# s a - Int# - a - a - State# s - (# State# s, Int#, a #) casWord16MutByteArray :: MutableByteArray# s - Int# - Word# - Word# - State# s - (# State# s, Int#, Word#) FYI, I started working on adding these. I'm hoping to have it working in GHC HEAD for any students who need to use it. To my knowledge the only two patches required to implement casMutVar# were these two (plus the preexisting cas() definition in SMP.h): https://github.com/ghc/ghc/commit/521b792553bacbdb0eec138b150ab0626ea6f36b https://github.com/ghc/ghc/commit/606f6e1cfcb2e79abaadcc5ed643817d2a4585d8 The latter is a bugfix to the former. Florian, your proposal looks good to me ( http://www.google-melange.com/gsoc/proposal/review/google/gsoc2012/florianhartwig/1). You touched on the major things we need to know. I just read in your proposal that you started looking into the casMutArray# issue as well. How far have you gotten with that? Do you want to work on this together a bit? I've got an implementation of a casArray# primop that passes a basic test, but I'm not sure if the GC write barrier is correct: https://github.com/rrnewton/ghc/commit/18ed460be111b47a759486677960093d71eef386 The ByteArray versions will be more annoying, requiring more variations, but they are also less essential, because the user can always use ForeignPtr and bits-atomic in this case, and I believe for our concurrent data structures we want to store arbitrary pointers (hence casArray#). Cheers, -Ryan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
