2009/7/21 Conal Elliott
I'd like to use some OpenGL resources (VBOs, textures, shaders, and shader programs) in a functional way, with immutability, garbage collection, and IO-free creation interfaces. Has anyone played with doing such a thing? I guess the GC part would involve foreign pointers with foreign finalizers (which now run promptly in GHC iiuc). I don't know of any reliable way to add finalizers to Ptr values, because of the unboxing problem [1].
One tricky issue is that graphics context initialization must take place before any of these "pure" resources get evaluated. If the APIs allowed access to to multiple graphics contexts, things would get stickier.
Comments?
Hi, I wanted to point you to a paper (Stretching the storage manager: weak pointers and stable names in Haskell) but see you're one of the authors. As you say, there is the notion of context. I guess you can create the context with something explicitely in IO, like createContext :: IO Context then implementing the "pure" resources as data structure referencing the context. Anyway, I've not a clear picture of what you have in mind (especially, at which point in time a, say, VBO should be considered to be part of things to be rendered). Often, a data structure (say Blah) is created in a pure way then given to some kind of run :: Blah -> IO () function for "interpretation". Why not mirror the OpenGL API in a purely data-centric way then give the data to the run function ? Although the OpenGL C API is imperative, it maps fairly well to a data-centric approach.