On 26 January 2012 09:24, Christopher Brown
Hi Thomas,
By static semantics I mean use and bind locations for every name in the AST.
I'm steering towards haskell-src-exts right now as the sheer complexity of the ghc-api is putting me off. I need something simple, as I can't be spending all my time learning the ghc-api and hacking it together to do what I want. It does look a bit of a mess. Just trying to do simple things
Right, that's what the renamer does in GHC. The GHC AST is parameterised over the type of identifiers used. The three different identifier types are: - RdrName: is the name as it occurred in source code. This is the output of the parser. - Name: is basically RdrName + unique ID, so you can distinguish two "x"s bound at different locations (this is what you want). This is the output of the renamer. - Id: is Name + Type information and consequently is the output of the type checker. Diagram: String --parser--> HsModule RdrName --renamer--> HsModule Name --type-checker--> HsBinds Id Since you can't hook in-between renamer and type checker, it's perhaps more accurately depicted as: String --parser--> HsModule RdrName --renamer+type-checker--> (HsModule Name, HsBinds Id) The main reasons why it's tricky to use the GHC API are: 1. You need to setup the environment of packages etc. E.g., the renamer needs to look up imported modules to correctly resolve imported names (or give a error). 2. The second is that the current API is not designed for external use. As I mentioned, you cannot run renamer and typechecker independently, there are dozens of invariants, there are environments being updated by the various phases, etc. For example, if you want to generate code it's probably best to either generate HsModure RdrName or perhaps the Template Haskell API (never tried that path). like parsing a file and showing its output proved to be much more complicated than it really needed to be
We have decided to take it on. :)
Could you clarify that? Are you doing everything in haskell-src-exts or are you using the GHC API and translate the result into haskell-src-exts? The former might be easier to implement, the latter could later be extended to give you type info as well (without the need to implement a whole type checker that most likely will bit rot compared to GHC sooner or later). / Thomas -- Push the envelope. Watch it bend.