On Mon, 2004-01-19 at 11:34, Simon Marlow wrote:
For the Visual Studio plugin we're going to need to talk to GHCi. We plan to do this by designing an appropriate API for GHCi and calling it directly; you *could* do it by talking over a pipe, but it's going to be a lot of work (and slow). If you want to do this, please talk to us about what API you'd like to see, and we can hopefully implement something that will be generally useful.
I wanted something like that for a Haskell IDE I was working on (not much progress on it at the moment, but I may pick it up again).
The main things I wanted was enough information to be able to implement "jump to definition". Where you select a symbol in your editor and move to where that variable/function/type/class was defined, in the same module or another module. It would also be useful to find out the module and package a symbol comes from so that an IDE could have a good stab at finding some documentation.
For that, you'd want an API for wandering through the useful information in .hi files. An API corresponding to hugs/ghci's :info <name>, :browse <modname>, :type <name> would be a good start. You'd want to be able to specify which root module to load up the symbols for, optionally specifing a search path and expect it to also load up the .hi files for any imported modules.
This is all stuff that we need for Visual Studio too. VS will typecheck your program as you type, so you'll get errors underlined in the source code. A side effect of this is that it will collect all the information reuqired to implement "jump to definition" and "tell me the type of this identifier" in the editor. My plan is to have an API where you can request a :load of a module source (perhaps omitting the code generation steps for speed) and then request information about the module, by source location (GHC now has completely accurate source location information in its abstract datatype; we did this recently in order to support the Visual Studio work). The API will most likely be a derivative of the existing compilation manager interface: see ghc/compiler/compMan/CompManager.lhs. Cheers, Simon