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Live recompiler for Haskell
Halive uses the GHC API to instantly recompile and reload your code any time you change it.
Usage:
cabal install halive
and then
halive <path/to/mymain.hs> <extra-include-dirs>
Any time you change a file in the current directory or its subdirectories,
halive will recompile and rerun the main function in the file you gave it.
If the program is long-running (e.g. a daemon, GUI or game loop) it will be killed and restarted. Learn how to maintain state in the next section.
Try a live-coding GL demo by running halive demo/Main.hs (in the source package)
and changing values in Main.hs and Green.hs
(requires gl, GLFW-b, foreign-store, linear, and random).
Keeping values alive
To keep state alive, import Halive.Utils and wrap
your value in reacquire along with a unique identifier, like:
win <- reacquire 0 (setupGLFW "HotGLFW" 640 480)
to only create the resource the first time you run the program, and then reuse it on subsequent recompilations.
You can see this in action in demo/Main.hs.
Thanks to Chris Done's
foreign-store
library for enabling this.
Passing command-line arguments
To use Halive with haskell code that is expecting command-line arguments,
separate the arguments to Halive and the argumetns to the app with a --
such as:
halive <path/to/mymain.hs> <extra-include-dirs> -- <args-to-myapp>
Notes
Creating, updating, and deleting modules in the include path should work fine during a Halive session.
Halive also supports Cabal sandboxes; if run within a directory containing a cabal.sandbox.config file it will use the package database defined therein.
Halive also works nicely with either batch-processing or run-loop type programs — if the program finishes, it will be restarted on next save, and if it's still running, it will be killed and restarted on save.
To kill Halive during run-loop type programs, you may need to hold down Ctrl-C to get GHC to recognize the double-Control-C-kill sequence.