This would probably be a great boon for those trying to use haskell for Android and IOS right? how might the emulation setup work for those?
On Wed, Jul 2, 2014 at 2:20 PM, Carter Schonwald <carter.schonw...@gmail.com > wrote: > wow, this is great work! > > If theres a clear path to getting the generic tooling into 7.10, i'm all > for it :) (and willing to help on concrete mechanical subtasks) > > > On Wed, Jul 2, 2014 at 12:14 PM, Luite Stegeman <stege...@gmail.com> > wrote: > >> hi all, >> >> I've added some code [1] [2] to GHCJS to make it run Template Haskell >> code on node.js, rather than using the GHC linker. GHCJS has supported TH >> for a long time now, but so far always relied on native (host) code for it. >> This is the main reason that GHCJS always builds native and JavaScript code >> for everything (another is that Cabal Setup.hs scripts need to be compiled >> to some host-runnable form, but that can also be JavaScript if you have >> node.js) >> >> Now besides the compiler having to do twice the work, this has some other >> disadvantages: >> >> - Our JavaScript code has the same dependencies (packages) as native >> code, which means packages like unix or Win32 show up somewhere, depending >> on the host environment. This also limits our options in choosing >> JS-specific packages. >> - The Template Haskell code runs on the host environment, which might be >> slightly different from the target, for example in integer size or >> operating system specific constants. >> >> Moreover, building native code made the GHCJS installation procedure more >> tricky, making end users think about libgmp or libiconv locations, since it >> basically required the same preparation as building GHC from source. This >> change will make installing much easier and more reliable (we still have to >> update the build scripts). >> >> How it works is pretty simple: >> >> - When any code needs to be run on the target (hscCompileCoreExpr, >> through the Hooks API new in GHC 7.8), GHCJS starts a node.js process with >> the thrunner.js [3] script, >> - GHCJS sends its RTS and the Template Haskell server code [1] to >> node.js, the script starts a Haskell thread running the server, >> - for every splice, GHCJS compiles it to JavaScript and links it using >> its incremental linking functionality. The code for the splice, including >> dependencies that have not yet been sent to the runner (for earlier >> splices), is then sent in a RunTH [4] message, >> - the runner loads and runs the code in the Q monad, can send queries to >> GHCJS for reification, >> - the runner sends back the result as a serialized Template Haskell AST >> (using GHC.Generics for the Binary instances). >> >> All Template Haskell functionality is supported, including recent >> additions for reifying modules and annotations. I still need to clean up >> and push the patches for the directory and process packages, but after >> that, the TH code can read/write files, run processes and interact with >> them and make network connections, all through node.js. >> >> Now since this approach is in no way specific to JavaScript, I was >> wondering if there's any interest in getting this functionality into GHC >> 7.10 for general cross compilation. The runner would be a native (target) >> program with dynamic libraries (or object files) being sent over to the >> target machine (or emulator) for the splices. >> >> Thanks to Andras Slemmer from Prezi who helped build the initial proof of >> concept (without reification) at BudHac. >> >> cheers, >> >> Luite >> >> [1] >> https://github.com/ghcjs/ghcjs/blob/414eefb2bb8825b3c4c5cddfec4d79a142bc261a/src/Gen2/TH.hs >> [2] >> https://github.com/ghcjs/ghcjs-prim/blob/2dffdc2d732b044377037e1d6ebeac2812d4f9a4/GHCJS/Prim/TH/Eval.hs >> [3] >> https://github.com/ghcjs/ghcjs/blob/414eefb2bb8825b3c4c5cddfec4d79a142bc261a/lib/etc/thrunner.js >> [4] >> https://github.com/ghcjs/ghcjs-prim/blob/2dffdc2d732b044377037e1d6ebeac2812d4f9a4/GHCJS/Prim/TH/Types.hs#L29 >> >> _______________________________________________ >> Glasgow-haskell-users mailing list >> Glasgow-haskell-users@haskell.org >> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users >> >> >
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