[Haskell-cafe] How to use Template Haskell based on code that generated by another Template?
I have a yesod project, which generated, say, UserPassword in module Model. Then I wrote my template code which generate a piece of code to use UserPassword. I imported Model in my code. Then I got Illegal variable name: `UserPassword' When splicing a TH declaration: -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
Emscripten is meant to translate ANY LLVM IR code to javascript and it should work (as I belive). I've tried to compile 'hello wrold' Haskell program to JS using Emscripten but I faced a problem, that in generated LLVM IR code there is no C-like main function (https://github.com/kripken/emscripten/issues/500) so there has to be a runtime library that has to be linked and will run the code - is this RTS or something else? If its RTS I understeand I should compile it to javascript and then provide it as a library to emscripten? Do you have a working RTS js version? I want to simply try emscripten and see how it performs on such GHC generater LLVM IRs. 2013/7/2 Luite Stegeman stege...@gmail.com On Tue, Jul 2, 2013 at 4:38 PM, B B blackbox.dev...@gmail.com wrote: Thank you for all the replies. Luite Stegeman - I was thinking that the LLVM IR code is optimized already or you can run LLVM IR optimization passes to get rid of such things. I think compiling with ghc -fllvm generates LLVM bitcode and then you can simply run emscripten on it to get Javascript - and it should work as expected. Most of the optimizations that GHC does are on Core, so you also get those if you use Core or STG as the source. You do miss out on the later optimization passes (GHC optimizes Cmm with Hoopl, and LLVM optimizes again). We implement this in GHCJS ourselves, optimizing the generated JavaScript. Since GHC itself is written in Haskell, it would be a good goal to compile simple Haskell programs first and make sure that the RTS is working (you'll need to compile the Cmm and C RTS files to LLVM). You can try to get the GHC Testsuite [1] running. The GHCJS testsuite [2] might also be useful, it contains much of the GHC Testsuite and a runner program that checks the JavaScript results against native Haskell. Like i said in the previous post, the generated code is a bit weird: stacks are allocated dynamically, functions never return, there are only tail calls. Emscripten might have a hard time with this. [1] https://github.com/ghc/testsuite [2] https://github.com/ghcjs/ghcjs/tree/master/test ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
On Wed, Jul 3, 2013 at 11:06 AM, B B blackbox.dev...@gmail.com wrote: Emscripten is meant to translate ANY LLVM IR code to javascript and it should work (as I belive). It cannot compile ANY LLVM code: It's heavily geared towards porting C and C++ code to JavaScript, and still there are some limitatons, see: https://github.com/kripken/emscripten/wiki/CodeGuidelinesAndLimitations Also the FAQ mentions how event loops should be converted to something that emscripten can deal with: https://github.com/kripken/emscripten/wiki/FAQ Since the GHC runtime never returns, you'd probably have to do something similar. I've tried to compile 'hello wrold' Haskell program to JS using Emscripten but I faced a problem, that in generated LLVM IR code there is no C-like main function (https://github.com/kripken/emscripten/issues/500) so there has to be a runtime library that has to be linked and will run the code - is this RTS or something else? If its RTS I understeand I should compile it to javascript and then provide it as a library to emscripten? Do you have a working RTS js version? I don't have a working version. The files you need are probably mostly in the rts directory of the GHC repository: https://github.com/ghc/ghc/tree/master/rts , but you might need a bit more, like libffi and gmp (unless you use integer-simple). I want to simply try emscripten and see how it performs on such GHC generater LLVM IRs. I don't think it's that easy... I'd expect a few weeks of work minimum to get very simple examples like Hello, world working. And a few months for something big like GHC. Also keep in mind that the code will probably be pretty big, GHC (and GHCi, which is the same file) is ~65MB on my linux system, so getting well over 100MB of JavaScript wouldn't be terribly surprising. luite ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Liber Amicorum for Doaitse Swierstra.
Dear all, Prof. Doaitse Swierstra is retiring on August 1 of this year, and is leaving the very functional programming minded Software Technology group that he has led for many decades. We have compiled a Liber Amicorum in his honour that we handed to him after his farewell speech on May 30th. You can find a download of this book at: http://www.cs.uu.nl/people/jur/liberdoaitseswierstra.pdf Not all contributions are ``technical'', and not all of them are in English, but counting up the pages, I guess about 75 percent is. best, Jurriaan Hage ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
Thank you for your response :) Could you please answer one additional question - why you, while creating GHCJS didn't base on emscripten? Why haven't you patched it and created custom solution? Is GHCJS production ready? Also - Can I use GHCJS to compile big projects (like GHC or GHCI) to Javascript? When you mentioned the file sizes I thought it would be good to further introduce what we are trying to do. We want to be able to send a haskell code to a server to compile it and return the resulted JS to user as a compiled library. We want users to be able to connect these compiled functions together to get some interactive results. for example: user is creating 2 functions (pseudocode): a(x) and b(x). They are send to server and compiled to JS. Then in an online tool user is connecting (visually with lines) a data (lets say a list of ints) [] - a - b. While connecting it we want this tool to interpret such connections and visualise the data on each step - so we want to have some kind of runtime or interpreter on client side. 2013/7/3 Luite Stegeman stege...@gmail.com On Wed, Jul 3, 2013 at 11:06 AM, B B blackbox.dev...@gmail.com wrote: Emscripten is meant to translate ANY LLVM IR code to javascript and it should work (as I belive). It cannot compile ANY LLVM code: It's heavily geared towards porting C and C++ code to JavaScript, and still there are some limitatons, see: https://github.com/kripken/emscripten/wiki/CodeGuidelinesAndLimitations Also the FAQ mentions how event loops should be converted to something that emscripten can deal with: https://github.com/kripken/emscripten/wiki/FAQ Since the GHC runtime never returns, you'd probably have to do something similar. I've tried to compile 'hello wrold' Haskell program to JS using Emscripten but I faced a problem, that in generated LLVM IR code there is no C-like main function (https://github.com/kripken/emscripten/issues/500) so there has to be a runtime library that has to be linked and will run the code - is this RTS or something else? If its RTS I understeand I should compile it to javascript and then provide it as a library to emscripten? Do you have a working RTS js version? I don't have a working version. The files you need are probably mostly in the rts directory of the GHC repository: https://github.com/ghc/ghc/tree/master/rts , but you might need a bit more, like libffi and gmp (unless you use integer-simple). I want to simply try emscripten and see how it performs on such GHC generater LLVM IRs. I don't think it's that easy... I'd expect a few weeks of work minimum to get very simple examples like Hello, world working. And a few months for something big like GHC. Also keep in mind that the code will probably be pretty big, GHC (and GHCi, which is the same file) is ~65MB on my linux system, so getting well over 100MB of JavaScript wouldn't be terribly surprising. luite ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Catch multiple exceptions using 'Control.Exception'
I'm trying to update a package that uses 'Control.OldException' (works with GHC 6.10.4). Here is a relevant (and simplified) part: import Control.OldException -- | A predicate matching synchronous exceptions. syncExceptions :: Exception - Maybe Exception syncExceptions (AsyncException _) = Nothing syncExceptions e = Just e throwAsync :: IO a throwAsync = throwIO $ AsyncException StackOverflow throwArith :: IO a throwArith = throwIO $ ArithException DivideByZero 'syncExceptions' is usually used like this: *Main tryJust syncExceptions throwArith Left divide by zero *Main tryJust syncExceptions throwAsync -- pass through *** Exception: stack overflow The above doesn't work with GHC 7.6.3 because 'Control.OldException' [1] was removed. And 'Control.Exception' doesn't have the 'Exception' type. Is there a way to adapt 'syncExceptions' to work with 'Control.Exception'? [1] http://hackage.haskell.org/packages/archive/base/4.1.0.0/doc/html/Control-OldException.html pgpxks_kAP6YQ.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
On Wed, Jul 3, 2013 at 12:26 PM, B B blackbox.dev...@gmail.com wrote: Thank you for your response :) Could you please answer one additional question - why you, while creating GHCJS didn't base on emscripten? Why haven't you patched it and created custom solution? I didn't know a good way to get the tail calling to work, and also it looked like it would be hard to make it as convenient to use as higher level JavaScript (we can just wrap JS objects in Haskell thunks, insert foreign imports directly in the functions (example: [1] ). That said, asm.js/emscripten have progressed a lot since I started working on this (I started on the 'gen2' code generator in August last year). Perhaps when JS gets native tail calls, it might be time to give LLVM/emscripten another look. Is GHCJS production ready? Also - Can I use GHCJS to compile big projects (like GHC or GHCI) to Javascript? I think GHCJS should be able to compile all Haskell code in GHC, but we haven't tested this yet. The tricky bit is probably getting foreign code work, and creating a working installation that includes all other things, like libraries and a package database. Usually, GHCi loads object files for the libraries when running Haskell code. Obviously you can't run machine code with JavaScript, so you'd have to find a way around it. GHCJS includes an IO layer, which can be used to set up a virtual filesystem [2], but the API is far from finished. When you mentioned the file sizes I thought it would be good to further introduce what we are trying to do. We want to be able to send a haskell code to a server to compile it and return the resulted JS to user as a compiled library. We want users to be able to connect these compiled functions together to get some interactive results. Ah it's much easier if the code can be compiled on the server. This is more or less what Daniil Frumin is doing for his Google Summer of Code project [3]. We are using GHC on the server for non-interactive things, and GHCJS to compile interactive code that is run on the client. Our main goal is to get interactive graphics with the diagrams [4] library working. Currently he is working on building a good sandbox for the compiler on the server (With SELinux, rlimits and cgroups) so that we can compile code, and run Template Haskell safely. I'm working on improving the GHCJS linker, so that we can support incremental code loading more easily (so users can download just the code for the new function they wrote, instead of the whole program every time) for example: user is creating 2 functions (pseudocode): a(x) and b(x). They are send to server and compiled to JS. Then in an online tool user is connecting (visually with lines) a data (lets say a list of ints) [] - a - b. While connecting it we want this tool to interpret such connections and visualise the data on each step - so we want to have some kind of runtime or interpreter on client side. I have a very crude example of this type here: http://hdiff.luite.com/reduce/ It's hacked together in one day, replacing the GHCJS main loop with one that draws a graph of the stack and heap every reduction step. It could be much better obviously, with better forward backward stepping/tracing and more information about the objects, and of course improved presentation. When we have the SELinux sandbox working, I plan to work on this again, so that users can enter/compile their own code. luite [1] Foreign import javascript example: https://github.com/ghcjs/ghcjs-jquery/blob/03b71effaeb059c9847306c93d69839588354134/JavaScript/JQuery/Internal.hs#L119 [2] GHCJS IO Layer: https://github.com/ghcjs/shims/blob/master/src/io.js [3] Daniil Frumin's GSoC project: https://github.com/co-dan/interactive-diagrams [4] Diagrams library: http://projects.haskell.org/diagrams/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Catch multiple exceptions using 'Control.Exception'
Perhaps you can use `catches` [0]? Erik [0] http://hackage.haskell.org/packages/archive/base/latest/doc/html/Control-Exception.html#v:catches On Wed, Jul 3, 2013 at 12:47 PM, Nikita Karetnikov nik...@karetnikov.org wrote: I'm trying to update a package that uses 'Control.OldException' (works with GHC 6.10.4). Here is a relevant (and simplified) part: import Control.OldException -- | A predicate matching synchronous exceptions. syncExceptions :: Exception - Maybe Exception syncExceptions (AsyncException _) = Nothing syncExceptions e = Just e throwAsync :: IO a throwAsync = throwIO $ AsyncException StackOverflow throwArith :: IO a throwArith = throwIO $ ArithException DivideByZero 'syncExceptions' is usually used like this: *Main tryJust syncExceptions throwArith Left divide by zero *Main tryJust syncExceptions throwAsync -- pass through *** Exception: stack overflow The above doesn't work with GHC 7.6.3 because 'Control.OldException' [1] was removed. And 'Control.Exception' doesn't have the 'Exception' type. Is there a way to adapt 'syncExceptions' to work with 'Control.Exception'? [1] http://hackage.haskell.org/packages/archive/base/4.1.0.0/doc/html/Control-OldException.html ___ 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] Catch multiple exceptions using 'Control.Exception'
Perhaps you can use `catches` [0]? Maybe, but my idea is to replace 'syncExceptions' with a similar function. Otherwise, it'll be necessary to change (at least) all functions that use 'syncExceptions'. I'd like to avoid that. pgp3z2Qli9UKD.pgp Description: PGP signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Custom Setup.hs and Paths module
Hello Erik. Yes, that solution may work, but seems ad-hoc to me. I would like to see a way to actually import the Paths module. In the meanwhile, I will be using your idea. Thank you for the response. Anybody knows how to hack the Setup.hs so I can use the real Paths module? On Wed, Jul 3, 2013 at 3:39 AM, Erik de Castro Lopo mle...@mega-nerd.comwrote: Daniel Díaz Casanueva wrote: Hi everyone. I am writing a package where I am using the Paths module that cabal generates automatically. After adding the Paths module to the other-modules section in my cabal file everything worked just fine, until I wanted to write a custom Setup.hs. This Setup.hs just writes a couple of files in the system and then calls defaultMain. The thing is that now cabal install does not find the Paths module, so the package is broken. I ran into the same problem. I ended up fixing it by *not* using the auto generated Paths module and instead parsing the cabal file in Setup.hs. This is not has horrible as it sounds as I used the Cabal insfrastructure to do it. Basically something like this: import Distribution.Simple import Distribution.PackageDescription import Distribution.PackageDescription.Parse (readPackageDescription) import Distribution.Verbosity (silent) version - fmap (showVersion . pkgVersion . package . packageDescription) $ readPackageDescription silent my-package.cabal and then used that version String to write a trivial 5 line file Version.hs. HTH, 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] ghci ghc - JS (Emscripten)
I think GHCJS should be able to compile all Haskell code in GHC, but we haven't tested this yet. The tricky bit is probably getting foreign code work, and creating a working installation that includes all other things, like libraries and a package database. Usually, GHCi loads object files for the libraries when running Haskell code. Obviously you can't run machine code with JavaScript, so you'd have to find a way around it. GHCJS includes an IO layer, which can be used to set up a virtual filesystem [2], but the API is far from finished. Nice to hear that - we are concidering using GHCJS heavly in our project. We dont have many people and this is free-time driven project for now, but we would love to cooperate with you - help with GHCJS development and work together to make it suitable for the project we are working on. Ah it's much easier if the code can be compiled on the server. This is more or less what Daniil Frumin is doing for his Google Summer of Code project [3]. We are using GHC on the server for non-interactive things, and GHCJS to compile interactive code that is run on the client. Our main goal is to get interactive graphics with the diagrams [4] library working. Currently he is working on building a good sandbox for the compiler on the server (With SELinux, rlimits and cgroups) so that we can compile code, and run Template Haskell safely. I'm working on improving the GHCJS linker, so that we can support incremental code loading more easily (so users can download just the code for the new function they wrote, instead of the whole program every time) That's very interesting. We want to use GHCJS EXACTLY for this - we want to compile the code on the server and run it in the users browesr BUT we dont want to load the whole program everytime a function is changed - only this particular function. Additional (which is NOT the same) - while writing a function - we want to interactively execute it's body on the client side - but this requires something like interpreter on the user client (please see below for explanation). But we are thinking right now about it and its architecture, so we will be in touch in this topic with you :) I have a very crude example of this type here: http://hdiff.luite.com/reduce/ This is not exactly the kind of thing I'm talking about. Think about something like matlab simulink or labview - functions are representaed by nodes (rectangles) connected with other functions by lines. Lines are sending data between these nodes. So user is connecting these blocks - each block is like a function application on data - so adding a block is like adding a new line in Haskell .hs file. We want user to be able to interactively add such nodes (apply further functions on already processed and cached data - every node caches processed data) and process the data further - If I didn't explained this simple enought, I will try harder. Such thing needs something like client side interpreter I think ... When we have the SELinux sandbox working, I plan to work on this again, so that users can enter/compile their own code. When do you plan roughtly to release it? We are strongly interested in testing and using it :) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
On Wed, Jul 3, 2013 at 6:26 AM, B B blackbox.dev...@gmail.com wrote: Could you please answer one additional question - why you, while creating GHCJS didn't base on emscripten? Why haven't you patched it and created custom solution? I'd like to point out that the LLVM code from GHC is CPS-transformed, and this makes it a nightmare to work with. Already the LLVM optimizer pretty much fails to do anything: optimizing CPS-transformed code is well-nigh impossible without knowing what the pre-transformation code was, which means a GHC-specific optimizer is necessary, or some way to communicate the code's structure (LLVM actually supports annotations for this, but current GHC doesn't generate them; I also would expect those annotations to go only so far without GHC-specific tweaks to LLVM, and in fact I am under the impression such tweaks have been proposed for inclusion in LLVM). Similarly I would expect that generating any sort of sensible Javascript would require something fairly tightly tied to GHC; otherwise the output's going to have horrible performance because it's not going to understand the input and will fall back to the slowest but most general translation. (If it even has such a fallback, instead of simply failing on code that it doesn't recognize.) -- brandon s allbery kf8nh sine nomine associates allber...@gmail.com ballb...@sinenomine.net unix, openafs, kerberos, infrastructure, xmonadhttp://sinenomine.net ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
On Wed, Jul 3, 2013 at 3:13 PM, B B blackbox.dev...@gmail.com wrote: I think GHCJS should be able to compile all Haskell code in GHC, but we haven't tested this yet. The tricky bit is probably getting foreign code work, and creating a working installation that includes all other things, like libraries and a package database. Usually, GHCi loads object files for the libraries when running Haskell code. Obviously you can't run machine code with JavaScript, so you'd have to find a way around it. GHCJS includes an IO layer, which can be used to set up a virtual filesystem [2], but the API is far from finished. Nice to hear that - we are concidering using GHCJS heavly in our project. We dont have many people and this is free-time driven project for now, but we would love to cooperate with you - help with GHCJS development and work together to make it suitable for the project we are working on. Great, if you want to help or discuss, you can come to #ghcjs on freenode. This is not exactly the kind of thing I'm talking about. Think about something like matlab simulink or labview - functions are representaed by nodes (rectangles) connected with other functions by lines. Lines are sending data between these nodes. I think it's possible to trap function application and show inputs and outputs that way, but it might be tricky (maybe some patching required). Also the generated optimized code can be quite different from the original Haskell. There is lots of inlining, let floating and specialization, and all functions that use typeclasses get extra parameters for the dictionaries for example, so i guess trying to visualize everything automatically will not give you the results you're after. So user is connecting these blocks - each block is like a function application on data - so adding a block is like adding a new line in Haskell .hs file. We want user to be able to interactively add such nodes (apply further functions on already processed and cached data - every node caches processed data) and process the data further - If I didn't explained this simple enought, I will try harder. Such thing needs something like client side interpreter I think ... You could let the user edit functions, then call back to the server and get back graph nodes (and the code to run them of course), which could show the name and the correct number of inputs. Actually connecting them would require a typechecker though (and changing one connection can of course make other connections invalid), perhaps through a server callback. If you want to work with cached data, you probably want to use some special thing to connect the functions, since Haskell code generally does not do that. Perhaps FRP can be an inspiration here, where your graph editor wraps pure Haskell functions (written by the user) in behaviours, and changing values or behaviours propagates changes through the FRP network. When we have the SELinux sandbox working, I plan to work on this again, so that users can enter/compile their own code. When do you plan roughtly to release it? We are strongly interested in testing and using it :) The current code is already on github, but it does not quite work yet (and using it is not recommended until we are confident in the security of the sandbox). Daniil will probably blog about it soon, and we should have a public beta within a month. luite ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to use Template Haskell based on code that generated by another Template?
On Wed, Jul 3, 2013 at 2:25 AM, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Then I got Illegal variable name: `UserPassword' When splicing a TH declaration: Hi Magicloud, GHC seems to be trying to tell you that variables are lowercase in haskell. Since you don't have code, I'm guessing your error is from doing something like: wrong1 = print ($(dyn Just) 5) wrong2 = print ($(varE 'Just) 5) Which is a compile time error since you apparently can't pass a Name which is capitalized to `VarE :: Name - Exp' Any of these options work. They use the `ConE :: Name - Exp' constructor instead: opt1 = print ($(conE (mkName Just)) 5) opt2 = print ($(conE 'Just) 5) opt3 = print ($( [| Just |]) 5 ) -- Adam ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghci ghc - JS (Emscripten)
Similarly I would expect that generating any sort of sensible Javascript would require something fairly tightly tied to GHC; otherwise the output's going to have horrible performance because it's not going to understand the input and will fall back to the slowest but most general translation. (If it even has such a fallback, instead of simply failing on code that it doesn't recognize.) Emscripten produces a limited subset of JavaScript (asm.js), and Firefox has an optimizer specifically for that. It could result in good performance, but the CPS transformed code is still a problem indeed, so it's unclear if GHC generated code would work at all. Asm.js is really limited, it's like a far less convenient LLVM without modern instructions in JavaScript syntax. You can't use objects, everything is stored in a global heap array. Interestingly, Firefox performs far worse than Chrome and Safari on the current GHCJS code, probably because their garbage collector is rather poor (non-generational), and Haskell code produces lots of short-lived immutable objects. luite ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GHC 7.8 (GHCJS)
Hi, on the GHCJS website () I found an information: If you are from the future, you have GHC 7.8 or higher installed, and Cabal 1.18, run the following: $ cabal install ghcjs $ ghcjs-boot --auto Is it possible currently to get somehow GHC 7.8 or this information means that AFTER release of 7.8 this functionality will be available? ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHC 7.8 (GHCJS)
That's just a joke, because GHCJS is a bit tricky to install, but it will be easier after 7.8 is released and they have merged our patches (unless you really are from the future, then you can just install it, but please send me the code of all the bugs i'll have fixed by then). The easiest way to get up and running is a virtual machine with GHC HEAD, see this for some introduction and installation instructions: http://weblog.luite.com/wordpress/?p=14 For working on a VM, the vado tool might be useful: http://parenz.wordpress.com/2013/06/29/vado/ luite On Wed, Jul 3, 2013 at 5:53 PM, B B blackbox.dev...@gmail.com wrote: Hi, on the GHCJS website () I found an information: If you are from the future, you have GHC 7.8 or higher installed, and Cabal 1.18, run the following: $ cabal install ghcjs $ ghcjs-boot --auto Is it possible currently to get somehow GHC 7.8 or this information means that AFTER release of 7.8 this functionality will be available? ___ 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] ghci ghc - JS (Emscripten)
On Jul 3, 2013, at 5:13 PM, B B blackbox.dev...@gmail.com wrote: I think GHCJS should be able to compile all Haskell code in GHC, but we haven't tested this yet. The tricky bit is probably getting foreign code work, and creating a working installation that includes all other things, like libraries and a package database. Usually, GHCi loads object files for the libraries when running Haskell code. Obviously you can't run machine code with JavaScript, so you'd have to find a way around it. GHCJS includes an IO layer, which can be used to set up a virtual filesystem [2], but the API is far from finished. Nice to hear that - we are concidering using GHCJS heavly in our project. We dont have many people and this is free-time driven project for now, but we would love to cooperate with you - help with GHCJS development and work together to make it suitable for the project we are working on. Ah it's much easier if the code can be compiled on the server. This is more or less what Daniil Frumin is doing for his Google Summer of Code project [3]. We are using GHC on the server for non-interactive things, and GHCJS to compile interactive code that is run on the client. Our main goal is to get interactive graphics with the diagrams [4] library working. Currently he is working on building a good sandbox for the compiler on the server (With SELinux, rlimits and cgroups) so that we can compile code, and run Template Haskell safely. I'm working on improving the GHCJS linker, so that we can support incremental code loading more easily (so users can download just the code for the new function they wrote, instead of the whole program every time) That's very interesting. We want to use GHCJS EXACTLY for this - we want to compile the code on the server and run it in the users browesr BUT we dont want to load the whole program everytime a function is changed - only this particular function. Additional (which is NOT the same) - while writing a function - we want to interactively execute it's body on the client side - but this requires something like interpreter on the user client (please see below for explanation). But we are thinking right now about it and its architecture, so we will be in touch in this topic with you :) I have a very crude example of this type here: http://hdiff.luite.com/reduce/ This is not exactly the kind of thing I'm talking about. Think about something like matlab simulink or labview - functions are representaed by nodes (rectangles) connected with other functions by lines. Lines are sending data between these nodes. So user is connecting these blocks - each block is like a function application on data - so adding a block is like adding a new line in Haskell .hs file. We want user to be able to interactively add such nodes (apply further functions on already processed and cached data - every node caches processed data) and process the data further - If I didn't explained this simple enought, I will try harder. Such thing needs something like client side interpreter I think ... When we have the SELinux sandbox working, I plan to work on this again, so that users can enter/compile their own code. When do you plan roughtly to release it? We are strongly interested in testing and using it :) As Luite has pointed out we plan on releasing the first public beta within a month and we are hoping to ship full-featured easily extensible documented version by the end of the summer. ___ 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] Custom Setup.hs and Paths module
Daniel Díaz Casanueva wrote: Hello Erik. Yes, that solution may work, but seems ad-hoc to me. I would like to see a way to actually import the Paths module. In the meanwhile, I will be using your idea. Thank you for the response. Anybody knows how to hack the Setup.hs so I can use the real Paths module? I'm almost certain it can't be done. The problem is that the Paths module is generated by the 'cabal configure' process and the configure process needs to run Setup.hs which needs the Paths module etc etc. That's what you might call a circular dependency :-). 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
Re: [Haskell-cafe] Catch multiple exceptions using 'Control.Exception'
* Nikita Karetnikov nik...@karetnikov.org [2013-07-03 15:50:16+0400] Perhaps you can use `catches` [0]? Maybe, but my idea is to replace 'syncExceptions' with a similar function. Otherwise, it'll be necessary to change (at least) all functions that use 'syncExceptions'. I'd like to avoid that. Here you go: import Control.Exception import Data.Typeable syncExceptions :: SomeException - Maybe SomeException syncExceptions e | Just _ - cast e :: Maybe AsyncException = Nothing | otherwise = Just e Roman ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Weekly News: Issue 272
Welcome to issue 272 of the HWN, an issue covering crowd-sourced bits of information about Haskell from around the web. This issue covers the week of June 23 to 29, 2013. Quotes of the Week * kmc: johnw: I'm rejoining this channel after months away just to tell you how incredibly wrong you are that monads are the core concept of Haskell * dmwit: semigroups are monoids with an identity crisis * olsner: I think doing eta something means to make it more or less pointless. But I don't recall which eta does what * mm_freak: Oleg knows what's at the end of foldr f z [1..]. * copumpkin: it's like grasping desperately for the rope of induction as you fall down the bottomless pit of coinduction Top Reddit Stories * From zero to cooperative threads in 33 lines of Haskell code Domain: haskellforall.com, Score: 78, Comments: 39 On Reddit: [1] http://goo.gl/rtkrO Original: [2] http://goo.gl/wgyAC * RSS reader written in Haskell and Ur/Web Domain: bazqux.com, Score: 66, Comments: 38 On Reddit: [3] http://goo.gl/sUw1U Original: [4] http://goo.gl/gdh5G * FP Haskell Center -- full video demo -- app development, automatic deployment, Git and GitHub integration Domain: youtube.com, Score: 64, Comments: 68 On Reddit: [5] http://goo.gl/gBi5l Original: [6] http://goo.gl/TlGL9 * Building LLVM using Shake Domain: neilmitchell.blogspot.ca, Score: 54, Comments: 6 On Reddit: [7] http://goo.gl/38rWZ Original: [8] http://goo.gl/tA5tM * Hasochism: The Pleasure and Pain of Dependently Typed Haskell Programming [pdf] Domain: personal.cis.strath.ac.uk, Score: 52, Comments: 8 On Reddit: [9] http://goo.gl/6dDsL Original: [10] http://goo.gl/ZZPZL * GHC Core by example, episode 1 - Hello Core! Domain: alpmestan.com, Score: 46, Comments: 3 On Reddit: [11] http://goo.gl/iL5ho Original: [12] http://goo.gl/mUiO5 * HPCwire: Lustre Founder Spots Haskell on HPC Horizon Domain: hpcwire.com, Score: 36, Comments: 2 On Reddit: [13] http://goo.gl/h2dmv Original: [14] http://goo.gl/1WLf8 * Adventures in Three Monads - Logic, Prompt, Failure Domain: web.mit.edu, Score: 33, Comments: 8 On Reddit: [15] http://goo.gl/JEOfw Original: [16] http://goo.gl/AI5wV * Darcs' source code is some of the cleanest Haskell I've read in a while Domain: github.com, Score: 32, Comments: 13 On Reddit: [17] http://goo.gl/TWWMh Original: [18] http://goo.gl/fZGE8 * I accidentally the entire heap: debugging Haskell programs with space leaks Domain: bitba.se, Score: 32, Comments: 6 On Reddit: [19] http://goo.gl/9Vtzy Original: [20] http://goo.gl/HCS5N * GHCJS introduction – Concurrent Haskell in the browser Domain: weblog.luite.com, Score: 30, Comments: 4 On Reddit: [21] http://goo.gl/Fk8Xd Original: [22] http://goo.gl/8CUVT * Functional Reactive Web Interfaces with GHCJS and sodium Domain: weblog.luite.com, Score: 29, Comments: 12 On Reddit: [23] http://goo.gl/5QKn0 Original: [24] http://goo.gl/VpAOv * Who Ya Gonna Call? Getting Dirty with Cmm, the GHC backend, and writing new PrimOps with Carter Schonwald (at NY-Haskell) Domain: vimeo.com, Score: 26, Comments: 14 On Reddit: [25] http://goo.gl/wUVcs Original: [26] http://goo.gl/cZaGd * Business system using functional programming? Domain: self.haskell, Score: 24, Comments: 44 On Reddit: [27] http://goo.gl/QcE5P Original: [28] http://goo.gl/QcE5P * The Resource Applicative Domain: haskellforall.com, Score: 23, Comments: 16 On Reddit: [29] http://goo.gl/G7TIs Original: [30] http://goo.gl/4e0Gm Top StackOverflow Questions * What's the conceptual difference between Machines and Conduits (or other similar libraries)? votes: 13, answers: 1 Read on SO: [31] http://goo.gl/hrNMl * “inject” progress logging/tracing in haskell computation? votes: 13, answers: 2 Read on SO: [32] http://goo.gl/RdEKU * Difference between free monads and fixpoints of functors? votes: 12, answers: 0 Read on SO: [33] http://goo.gl/O3oBi * Can Haskell optimize function calls the same way Clang / GCC does? votes: 12, answers: 3 Read on SO: [34] http://goo.gl/Sgf88 * Trying to figure out `random` function in Haskell votes: 10, answers: 3 Read on SO: [35] http://goo.gl/kcHsi * What does !( ) means in data constructor? votes: 9, answers: 2 Read on SO: [36] http://goo.gl/ysnNL * Anything prevents optimizing tail-recursion? votes: 9, answers: 1 Read on SO: [37] http://goo.gl/LaTY2 * Where can I find a good introduction to Haskell optimization passes? votes: 9, answers: 1 Read on SO: [38] http://goo.gl/wMYQH * Passing void * through haskell votes: 9, answers: 1 Read on SO: [39] http://goo.gl/Fiu5Q * Call main function
[Haskell-cafe] bug in Data.ByteString.Lazy or in me?
On a 64-bit Windows 8 server EC2 instance, with Haskell Platform freshly installed from the package installer, GHCI :m + Data.ByteString.Lazy GHCI Data.ByteString.Lazy.hGetContents stdin gives me an immediate error hGetBufSome: resource exhausted (Not enough space), while GHCI :m + Data.ByteString GHCI Data.ByteString.hGetContents stdin waits for user input, as expected. On 32-bit Windows, both work as expected. Can anyone explain this? Is this a bug in bytestring? John ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Product-Categories
Hi Café. I'm wracking my brain trying to figure out a simple, reasonably general, implementation for a category instance for pairs of categories. So far I've looked at [1], which seems great, but doesn't use the built-in category instance, and [2], which I'm just not sure about. Ideally I'd like to be able to express something like - instance (Category a, Category b) = Category (Product a b) where id = Product id id Product o1 o2 . Product i1 i2 = Product (o1 . i1) (o2 . i2) However, it all falls apart when I actually try to define anything. Is this possible? If not, why not? As far as I can tell the issue boils down to not being able to translate Category i o to Product (Fst i) (Fst o) (Snd i) (Snd o) without breaking the kind expectation of the category instance. Please help me, I'm having a bad brain day :-) [1] - http://twanvl.nl/blog/haskell/categories-over-pairs-of-types [2] - http://hackage.haskell.org/packages/archive/categories/1.0.6/doc/html/Control-Category-Cartesian.html#t:Product ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] How to use Template Haskell based on code that generated by another Template?
Yes, I misunderstood the generated code and splice shown in error message. Thanks. On Wed, Jul 3, 2013 at 11:04 PM, adam vogt vogt.a...@gmail.com wrote: On Wed, Jul 3, 2013 at 2:25 AM, Magicloud Magiclouds magicloud.magiclo...@gmail.com wrote: Then I got Illegal variable name: `UserPassword' When splicing a TH declaration: Hi Magicloud, GHC seems to be trying to tell you that variables are lowercase in haskell. Since you don't have code, I'm guessing your error is from doing something like: wrong1 = print ($(dyn Just) 5) wrong2 = print ($(varE 'Just) 5) Which is a compile time error since you apparently can't pass a Name which is capitalized to `VarE :: Name - Exp' Any of these options work. They use the `ConE :: Name - Exp' constructor instead: opt1 = print ($(conE (mkName Just)) 5) opt2 = print ($(conE 'Just) 5) opt3 = print ($( [| Just |]) 5 ) -- Adam -- 竹密岂妨流水过 山高哪阻野云飞 And for G+, please use magiclouds#gmail.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Call for Demo Proposals: Workshop on Functional Art, Music, Modeling and Design
Hi all, Below is the call for demonstration proposals for FARM 2013. Please forward to anyone who might be interested -- apologies if you receive multiple copies! Brent Yorgey publicity chair for FARM 2013 == FARM 2013: Call for Demo Proposals ACM SIGPLAN Workshop on Functional Art, Music, Modeling and Design Boston, Massachusetts, USA 28th September, 2013 (directly after ICFP) http://www.cis.upenn.edu/~byorgey/farm13/ == Do you enjoy writing beautiful code to produce beautiful artifacts? Have something cool to show off at the intersection of functional programming and visual art, music, sound, modeling, visualization, or design? FARM 2013 is seeking proposals for 10-20 minute demonstrations to be given during the workshop. For example, a demonstration could consist of a short tutorial, an exhibition of some work, or even a livecoding performance. Slots for demonstrations will be shorter than slots for accepted papers, and will not be published as part of the formal proceedings, but can be a great way to show off interesting work and get feedback from other workshop participants. A demonstration slot could be a particularly good way to get feedback on work-in-progress. Scope - The functional programming community is largely interested in writing beautiful programs. This workshop is intended to gather researchers and practitioners interested in writing beautiful programs that generate beautiful artifacts. Such artifacts may include visual art, music, 3D sculptures, animations, GUIs, video games, physical models, architectural models, choreographies for dance, poetry, and even physical objects such as VLSI layouts, GPU configurations, or mechanical engineering designs. The framework used need not be purely functional (“mostly functional” is fine); may be based on abstractions such as higher-order functions, monads, arrows, or streams; and may be manifested as a domain specific language or tool. Theoretical foundations, language design, implementation issues, and applications are all within the scope of the workshop. Important dates --- - Demonstration proposals due: Wednesday, 31 July 2013, 18:00 EDT (UTC-4) - Author notification: Monday, 5 August 2013 - Workshop: Saturday, 28 September 2013 (the day after ICFP) A demo proposal should consist of a 1 page abstract, in PDF format, explaining the proposed content of the demonstration and why it would be of interest to the attendees of FARM. Proposals will be judged on interest and relevance to the stated goals and themes of the workshop. Submissions can be made via EasyChair at https://www.easychair.org/conferences/?conf=farm2013. Organizers -- Workshop Chair: Paul Hudak Program Chair: Conal Elliott Publicity Chair: Brent Yorgey Program Committee - Daniel Cukier (University of São Paulo) Conal Elliott (Tabula) (chair) Kathleen Fisher (Tufts University) Richard Gabriel (IBM Research) George Giorgidze (University of Tübingen) Paul Hudak (Yale University) José Pedro Magalhães (University of Oxford) Alex McLean (University of Leeds) John Peterson (Western State Colorado University) Michael Sperber (Active Group) Henning Thielemann Brent Yorgey (University of Pennsylvania) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
