Don Stewart
lazycat.manatee:
Hi all,
I'm research to build a hot-swap Haskell program to developing itself in Runtime, like Emacs.
Essentially, Yi/Xmonad/dyre solution is "replace currently executing" technology:
re-compile new code with new binary entry
when re-compile success $ do save state before re-launch new entry replace current entry with new binary entry (executeFile) store state after re-launch new entry
There are some problems with re-compile solution:
1) You can't save *all* state with some FFI code, such as gtk2hs, you can't save state of GTK+ widget. You will lost some state after re-launch new entry.
2) Sometimes re-execute is un-acceptable, example, you running some command in temrinal before you re-compile, you need re-execute command to restore state after re-launch, in this situation re-execute command is un-acceptable.
I wonder have a better way that hot-swapping new code without re-compile/reboot.
Well, the other approach to reloadable modules, using either object code plugins, or bytecode plugins, giving you module-level granularity. Thanks for your reply.
I have read your papers : "Dynamic Application From the Group Up" and "Plugging Haskell In" In "Dynamic Application From the Group Up", you introduction how to use re-compile technology implement source-code level hot-swapping. In "Plugging Haskell In", you introduction to how to buld hot-swapping with object-code level. Yes, Dynamic linking can add new code to a running program, but how to replace existing binding with new ones? Looks you still need some reboot when you do *replace* and not just *add*. Infact, reboot is okay, only problem is *keep state*, some *static state* is easier to re-build, example, if you want restore editor buffer state, you just need save (filepath, cursorPosition), you can re-open file and restore cursor position after reboot process. Difficult is *Stream State*, such as: delete operation in file-manager command running in temrinal network communications in browser It's really difficult to restore those state, and re-execute is un-acceptable sometimes. You can found the screenshot of my project at http://www.flickr.com/photos/48809572@N02/ Currently, the closest library to implement dynamic linking is your plugins package (http://hackage.haskell.org/package/plugins-1.4.1), i really want to write some code to test it, unfortunately, it's broken with Cabal-1.8.0.4 that can't compile with ghc-6.12.x/ghc-6.12.3, can you fix it if you have time? It's so great package... I'm looking for some paper about "Haskell and hot-swapping". Any paper or suggestion are welcome! -- Andy