Re: [Haskell-cafe] I would like to know how to use the following events handlers : dropTargetOnData, dropTargetOnDrop, dropTargetOnEnter,
If you have figured it all out, I hope you want to write a HaskellWiki page about it. If I pass the gating, I ll publish a kind some HowTo on the differente techniques I dig out already started with this one, where I published my finding in the answer: http://stackoverflow.com/questions/15867654/wx-haskell-drag-and-drop-example As no one else has responded so far, I think you are in uncharted territory; wxHaskell is huge and there are not many applications using it. good point. ! do we have some kind of census of application that wrok or still work with wxhaskell ? any interest in (me) doing this ? (who know some toosl to do this, a la doodle ?) and by extension : btw how many people are really active and resonably knowleadeable these day ? (e.g. senior) Are Eric ? Jeremy ? atzedijkstra ? yourself ? still active on wx. and are you using it yourself HenkJan ? is :https://github.com/atzedijkstra/wxHaskell the head dev for these day ? i.e. who is the maintainer ? ( Sorry for all these questions, but I am just discovering the field :-) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Organising code in FRP
I am just learning FRP ( via reactive-banana) . so possibly opening a topic already mentionned , apologises in advance, and pointers welcomed. I am wondering about code structuration ? ie spagetti code for the network 1/ in a non trivial FRP applicaiton, how to manage modulatity or structuration of the Network ? ( most of the example I scanned are toy-size). I ca imagine it may not be trvial to find its way around in a large setup ... 2/ what about the separation of layers. I mean fine, we extract the reactive ness from the GUI, and separate the layout of widgets from the behaviors of these great, but is it to then mingle the UI with the business part ( say in banking), and the infrastructure side ( say persistence, comms, transactionnality, etc) in other words, how tdoes the nice abstraction developped ( module/ interface / categoty patterns, monad, etc) coexsit with a netork of FRP event and behaviors ? Any prior art on this ? ( and which place si best to discuss this ?) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] graphical editor links ?
I am designing some graphical editor ( visio - dia like) and would be interested to hear any pointer to help me think on the architecture of this, in term of data structure/ EDSL/ persistence/ paradigm (FP/ FRP/...) for the different layers of abstraction I may see , like rendering libraries ( gtk/wx..)- model of the diagram- semantics ( this is a state diag/ archimate / mind mapping , i.e. what the glyph and lines means ) - persistence Any help pointers welcomed ! ( and which place is best to discuss this ?) Luc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] introducing Maybe at managing level
Thanks John. I was indeed thinking to Maybe and the monad bindings, and LYAH, or http://book.realworldhaskell.org/read/error-handling.html the problems is I cannot uses these links in isolation ( to a Non haskellers) because they mention Monads, Lazyness, Algebric types, all this vocabularies that side track a beginner, ( or a manager ;-) then all I want to show is the generic concept ( powerpoint level) of how a forest of (non core) case can be streamlined in one major case ( the good outcome) , and all the rest ( exceptions in a non technical sense) are catched by the maybe monad, without sidetracking the readability of the code . I saw this somewhere on the blogosphere, but cannot remember where.. this is management level, and this is even worse than beginners techies, because they derails very quickly when talking details -- Luc be.linkedin.com/in/luctaesch/ (http://be.linkedin.com/in/luctaesch/) Envoyé avec Sparrow (http://www.sparrowmailapp.com/?sig) Le vendredi 29 mars 2013 à 06:47, John Lato a écrit : In FP, I think this sort of problem is generally handled via algebraic data types rather than exceptions. In particular this directly addresses the issue of exceptions don't necessarily shout themselves out, since the compiler warns you if you've missed a case. They sound mathy, but algebraic data types are actually a pretty simple concept. I think the Learn You a Haskell explanation is decent: http://learnyouahaskell.com/making-our-own-types-and-typeclasses Provided I understand the context properly, actually using exceptions for this sort of issue would be extremely rare practice. On Fri, Mar 29, 2013 at 12:21 AM, luc taesch luc.tae...@gmail.com (mailto:luc.tae...@gmail.com) wrote: I was looking for some link introducing the way FP/ Haskell handles errors and Exceptions. This is for a non FP Guy, and ideally withought scaring them with Monads and category theory :-). for the background : the guy said : As I mentioned in another thread in banking (in particular) it is the exception processing that often dominates the functionality of a system - as the core concept is generally very straightforward. Developing for exception handling (not in a Java/C++ sense) is a tricky thing - as the exception don't necessarily shout themselves out - and are often why we have large misunderstood legacy systems which are hard to replace. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org (mailto: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] introducing Maybe at managing level
I was looking for some link introducing the way FP/ Haskell handles errors and Exceptions. This is for a non FP Guy, and ideally withought scaring them with Monads and category theory :-). for the background : the guy said : As I mentioned in another thread in banking (in particular) it is the exception processing that often dominates the functionality of a system - as the core concept is generally very straightforward. Developing for exception handling (not in a Java/C++ sense) is a tricky thing - as the exception don't necessarily shout themselves out - and are often why we have large misunderstood legacy systems which are hard to replace. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Make a DSL serializable
On 2013-03-25 19:00:42 +, Alberto G. Corona said: It is possible as long as there is a empty event and there is a operation that mix two events to créate an state and an operation that mix an state and a event to créate an state. I just read thisat a time I am learning FRP Reactive banana and these two collides : Workflow (Event, state) ~ FRP (Event, bahavior) is that anyway connected, Alberto ? ( workflow and FRP ) ( are worflow are serializable persitent FRP Network ?) - ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Haskell-Cafe Digest, Vol 115, Issue 37
Le dimanche 24 mars 2013, a écrit : Send Haskell-Cafe mailing list submissions to haskell-cafe@haskell.org javascript:; To subscribe or unsubscribe via the World Wide Web, visit http://www.haskell.org/mailman/listinfo/haskell-cafe or, via email, send a message with subject or body 'help' to haskell-cafe-requ...@haskell.org javascript:; You can reach the person managing the list at haskell-cafe-ow...@haskell.org javascript:; When replying, please edit your Subject line so it is more specific than Re: Contents of Haskell-Cafe digest... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] presentation on Diffusion of Innovation mentioning several times Haskell
Just found an Interesting presentation mixing Diffusion of Innovation with Social Patterns, mentioning several times Haskell. Good introduction to a mix of techniques for whoever interested in Haskell proselytism, and go to market strategy, http://www.taesch.com/haskell/go-to-market/introduction-to-diffusion-of-innovation-and-sociology-and-haskell-go-to-market-strategy/2013/02/24/276 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] capture of idioms and patterns
in real life I am doing architecture (appication and system) and I tend to see things differently with my haskell background. when reading what system XYZ does, I see folds, maps, lazy sort, memoisation , monads, etc...ie my mind apply idioms learned at code design level to architecture level So the following questions raised in me : - are there any prior art in documenting idioms and patterns in FP, and especially haskell. - have any work been done refering to architecture level , using these idioms, or FP specific architecture... (the idea germinated to extend the FP contiunum from code, design to architecture (and requirement) thank you, folks luc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: Re : Re: Re : Error importing
btw, this could be helpful, if you have some time: http://en.wikipedia.org/wiki/Cabal_(software) http://www.haskell.org/cabal/ in there you maay find : http://www.haskell.org/cabal/FAQ.html in which you can see ( hey !): Hidden packages (a)http://www.haskell.org/cabal/FAQ.html#hidden-packages-a What is this hidden package? You're writing your own package and you get: Could not find module `Data.Map': it is a member of package containers-0.1.0.0, which is hidden. Hidden packages (b)http://www.haskell.org/cabal/FAQ.html#hidden-packages-b You're building some other package and you get: Could not find module `Data.Map': it is a member of package containers-0.1.0.0, which is hidden. this is insteresting but maybe too advaced for now, may side track you. however may give you the big picture http://www.haskell.org/haskellwiki/How_to_write_a_Haskell_program besides, Howard, leksah is a small audience list, you may find more support on the cafe list, as your question as less leksah specific, but more on the haskell bootstrapping procees Ill copy you here, in case some good sould know some fast track ( btw , do you know about rwh : http://book.realworldhaskell.org/read/ especially http://book.realworldhaskell.org/read/installing-ghc-and-haskell-libraries.html#id688956 ) 2010/8/25 HowardBrazee how...@brazee.net Boy, am I dense. I see two depends lines in Reading.cabal: pkgconfig-depends: build-depends: base -any I uncommented out import qualified Data.Map as M and looked at Lekah's message: src\Main.hs:19:17: Could not find module `Data.Map': It is a member of the hidden package `containers-0.3.0.0'. Perhaps you need to add `containers' to the build-depends in your .cabal file. Use -v to see a list of the files searched for. So I put containers after one of the depends: build-depends: containers base -any Leksah said: Setup: .\Reading.cabal has been changed, please re-configure. = Setup: Reading.cabal:9: Parse of field 'build-depends' failed. = Can't activate package C:\Documents and Settings\brazee\My Documents \Code\Windows\Reading\Reading.cabal: 9: user error (Parse of field 'build-depends' failed.) Can't read package file So I undid that change and did this instead: pkgconfig-depends: containers I got the following: Can't read package file Setup: .\Reading.cabal has been changed, please re-configure. = Configuring Reading-0.0.1... Setup: pkg-config version =0.9.0 is required but it could not be found. = The job now runs with these unused imports. I never found build-depends in my cabal file. I edited this with ultra-edit as I know how to get to it. I'm still clueless about what I did, despite being told by two different people what to do and not being able to follow the directions, but doing trial and error instead. Even after I finished, I don't understand the directions. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Which Mail editor or mail chain do you use ?
Gentlemen, Slightly off topic, but when reading this list , I was ( happily ) surprised when reading this list, about the quality of typing, including redaction,paragraph, greeks and footnote ref like , in just a (pure) text list ... baskell[1] seems interesting. And there's hslua[2]. Can one use hint[3] like this ? Thanks [1] baskell - http://hackage.haskell.org/package/baskell [2] hslua - http://hackage.haskell.org/package/hslua [3] hint - http://hackage.haskell.org/package/hint Is this some kind of idiom that developped over time and habit ( of people reading papers) , particularly educated, and in need for others recognition, or born out of using an (arche)typical environment/ toolchain Markdown - latex like ? May I ask you how you redact your answers and which toolchain you are using ? Thanks for quenching my curiosity Luc ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] RE: what's the best environment for haskell work? (Rustom Mody)
On Sat, Jul 31, 2010 at 12:07 PM, Rustom Mody rustompm...@gmail.com wrote: Do most people who work with haskell use emacs/vi/eclipse or something else?? I used Emacs, as I used to in other langauages.( mainly on Linux) When switching to Mac Ox, I Re tried Leksah at 0.8 , and Now Am sticking to it. what I found of value: - In a Nutshell, increased focus. not only time, but focus. changes in my behavior , mainly : -when exploring unknown libraries, I found the one click access to libraries ( search Metadata) , then one click to read the source is easy (easier means then I do it more often). - the right click type this ... that seemlessly toogles betwwen ghi-ghci , is cool to paste types once a part of my code solidify - session saving means I find the same windows opened at the same place I left them the day before or a while ago... more focus again. ( when working in parallele on different things) ( Note : I have a 27 ' screen) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] arrows-.02 fails when rebuilding ghc 6.6.1
I try download and build 6.6.1 ( as ubntu has just 6.6 on package) and most went ok ( compiler and most libs) but arrows i tried and download arrow 0.2 from hackage but no more success any ideas ? ( knowing 6.6 is also on the machine if that matters) [EMAIL PROTECTED]:~/src/arrows-0.2$ runghc Setup.hs build Preprocessing library arrows-0.2... Building arrows-0.2... [ 1 of 13] Compiling Data.Stream ( Data/Stream.hs, dist/build/Data/Stream.o ) [ 2 of 13] Compiling Control.Arrow.Transformer ( Control/Arrow/Transformer.hs, dist/build/Control/Arrow/Transformer.o ) [ 3 of 13] Compiling Control.Arrow.Operations ( Control/Arrow/Operations.hs, dist/build/Control/Arrow/Operations.o ) [ 4 of 13] Compiling Control.Arrow.Transformer.CoState ( Control/Arrow/Transformer/CoState.hs, dist/build/Control/Arrow/Transformer/CoState.o ) [ 5 of 13] Compiling Control.Arrow.Internals ( Control/Arrow/Internals.hs, dist/build/Control/Arrow/Internals.o ) [ 6 of 13] Compiling Control.Arrow.Transformer.Automaton ( Control/Arrow/Transformer/Automaton.hs, dist/build/Control/Arrow/Transformer/Automaton.o ) Control/Arrow/Transformer/Automaton.hs:98:0: Illegal instance declaration for `ArrowWriter w (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowWriter w (Automaton a)' Control/Arrow/Transformer/Automaton.hs:104:0: Illegal instance declaration for `ArrowError r (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowError r (Automaton a)' Control/Arrow/Transformer/Automaton.hs:115:0: Illegal instance declaration for `ArrowReader r (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowReader r (Automaton a)' Control/Arrow/Transformer/Automaton.hs:120:0: Illegal instance declaration for `ArrowState s (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowState s (Automaton a)' Control/Arrow/Transformer/Automaton.hs:126:0: Illegal instance declaration for `ArrowAddWriter w (Automaton a) (Automaton a')' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowAddWriter w (Automaton a) (Automaton a')' I discovered recently that my ubuntu package were providing only 6.6 and the latest cabal needs 6.6.1. when rebuilding this one from the tar ( not the head on darcs) most went ok but the arrows lib. I also tried to get it from hackage, but idem: ( I also have 6.6 on the machaine dos it matters ?) here is the build from hacakge with runghc : [EMAIL PROTECTED]:~/src/arrows-0.2$ runghc Setup.hs build Preprocessing library arrows-0.2... Building arrows-0.2... [ 1 of 13] Compiling Data.Stream ( Data/Stream.hs, dist/build/Data/Stream.o ) [ 2 of 13] Compiling Control.Arrow.Transformer ( Control/Arrow/Transformer.hs, dist/build/Control/Arrow/Transformer.o ) [ 3 of 13] Compiling Control.Arrow.Operations ( Control/Arrow/Operations.hs, dist/build/Control/Arrow/Operations.o ) [ 4 of 13] Compiling Control.Arrow.Transformer.CoState ( Control/Arrow/Transformer/CoState.hs, dist/build/Control/Arrow/Transformer/CoState.o ) [ 5 of 13] Compiling Control.Arrow.Internals ( Control/Arrow/Internals.hs, dist/build/Control/Arrow/Internals.o ) [ 6 of 13] Compiling Control.Arrow.Transformer.Automaton ( Control/Arrow/Transformer/Automaton.hs, dist/build/Control/Arrow/Transformer/Automaton.o ) Control/Arrow/Transformer/Automaton.hs:98:0: Illegal instance declaration for `ArrowWriter w (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowWriter w (Automaton a)' Control/Arrow/Transformer/Automaton.hs:104:0: Illegal instance declaration for `ArrowError r (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowError r (Automaton a)' Control/Arrow/Transformer/Automaton.hs:115:0: Illegal instance declaration for `ArrowReader r (Automaton a)' (the Coverage Condition fails for one of the functional dependencies; Use -fallow-undecidable-instances to permit this) In the instance declaration for `ArrowReader r (Automaton a)'
[Haskell-cafe] Re: Ideas
thanks John for replying... when building , i cannot find the lcs mentionned in the cabal file not on hasckage nor on goggle. could you help? ( your papers on philosophy looks quite serious .. impressive you are in haskell too .. math backgroud ? logics ?) 2007/8/26, John MacFarlane [EMAIL PROTECTED]: may i ask you what did you had in mind as an application when you started that ? This was just recreational programming: I wanted to see what writing a web application in Haskell would be like. I think it would be great to have a fully featured wiki program in Haskell, but I don't have time to do it myself. Your idea sounds very interesting. Feel free to extend pandocwiki if that works for you; it's GPL. John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] latest cabal conflict?
when trying to build the latest cabal from darcs, I got [EMAIL PROTECTED]:~/src/cabinstall/cabal$ runghc Setup.lhs configure Distribution/Simple.hs:110:7: Could not find module `System.FilePath': it was found in multiple packages: filepath-1.0 FilePath-0.11 [EMAIL PROTECTED]:~/src/cabinstall/cabal$ sound like a conflict , i still have ghc 6.6, not 6.6.1. what should I do ? hide FilePath-0.11 in Distribution/Simple.hs imports ? ( and for all othe files? any way to just have FilePath out of the way via a Cabal statement? thks ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] IO in HApps handler ?
Subject: IO in HApps handler ? I am trying to add a handler that would run an external command in HApps 0.8.8, and I got a type issue I do not know how to get around.. can we have IO in a handler ? testcmdpost.hs:52:8: Couldn't match expected type `Ev st Request' against inferred type `IO' Expected type: ServerPart (Ev st Request) Request IO Result Inferred type: ServerPart IO Request im Result In the expression: (h [xxx] GET) $ (ok $ (\ () () - do (MySt val) - get runCommand ls [.] respond (show dfdf))) here is the handler iI am adding : ,h [xxx] GET $ ok $ \() () - do (MySt val) - get; runCommand ls [.]; respond (show dfdf ) in there : import HAppS.Util.Common... ... main :: IO () main = stdHTTP [debugFilter -- we want to see debug messages in the console ,h [] GET $ ok $ val GETting root hello -- ,h (Prefix [s]) GET $ respIO $ fileServe staticPath , hs (Prefix [s]) GET $ basicFileServe staticPath -- 0.8.8 -- /val shows us the current value ,h [val] GET $ ok $ \() () - do (MySt val) - get; respond (show val) -- /set with the POST data val=56 would set the value to 56 ,h [xxx] GET $ ok $ \() () - do (MySt val) - get; runCommand ls [.]; respond (show dfdf ) ,h [set] POST $ ok $ \() newVal - do put newVal; respond (New value is ++ show newVal) -- The first one is FromReqURI and the second one is FromMessage -- The cryptic comment about is referring to the arguments () and newVal -- to the method. The type of newVal being MyState is what -- invokes our custom FromMessage instance above. ] this is the runcommand from HAppS.Util.Common , not from defined as -- | Run an external command. Upon failure print status -- to stderr. runCommand :: String - [String] - IO () runCommand cmd args = do (_, outP, errP, pid) - runInteractiveProcess cmd args Nothing Nothing let pGetContents h = do mv - newEmptyMVar let put [] = putMVar mv [] put xs = last xs `seq` putMVar mv xs forkIO (hGetContents h = put) takeMVar mv os - pGetContents outP es - pGetContents errP ec - waitForProcess pid case ec of ExitSuccess - return () ExitFailure e - do hPutStrLn stderr (Running process ++unwords (cmd:args)++ FAILED (++show e++)) hPutStrLn stderr os hPutStrLn stderr es hPutStrLn stderr (Raising error...) fail Running external command failed ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] ghc 6.7 /6.8
Date: Sun, 19 Aug 2007 12:39:50 +0200 Subject: Fwd: ghc 6.7 /6.8 hello. will 6.7 be released, or will only 6.8 be ? ( i.e do you use an even/uneven relesing number convention) -in that case, does the 6.8 branch means the freeze is on, and what would be the target for 6.8 ? Q3/2007 ? Q4 ? ( context: I am impatient to test the new debbuger, but too newby to go and fix all the lib..hoping it may help me undertand haskell execution.. ) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Haskell as specification language
out of curiosity, is haskell already been used as a specification language ? i was thinking in a business term, rather than mathematical one. (i.e. one than normal mortal can read, even with a bit of training ;-) I.e. one would specifiy a model, an application ( possibly run it on samples), and hand it over to developper, typically in other languages/environment... I am aware of the contracts paper of SPJ, for instance... others you may think of ? does a spec. always leads to a DSL , for instance ? I imagine a specification for an application resulting in a DSL for the data model/ process model part, (which is the generic/ reusabel part, IMH) plus something more specific to the effective application targeted... (I cannot resist explaining my long term view : if IT outsourcing really takes off one day, one key factor will be proper specification, which is in a dear state in the current practice nowadays in the field) ref: http://search.ft.com/search/article.html?id=030923007625 ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
