Re: Integrating editline with ghc

Malcolm Wallace:

Christian Maeder wrote:

...

1. a _new_ readline package that only contains the interface that can be implemented using libeditline _or_ libreadline. If this package is call "readline" (with a new version number) most libraries i.e. like Shellac would not need modifications.

I totally agree. Backwards compatibility for all the programs out there that already use the readline package (but really don't care whether it is actually readline or editline) is vital. I would hate to see all client code forced to use CPP macros and cabal magic to select the right package and module imports. We can avoid such a retrograde step by explicitly making 'readline' the backend-agnostic package, which re-exports functionality from either the real readline or editline, depending on which is available.

I don't think we should touch the existing readline package. It's a binding to readline and whether everybody likes its license or not doesn't matter. Some people just want to use readline, and they should be able to continue to do this by importing the library called System.Console.Readline. In addition System.Console.Editline should be a binding to editline. (Again if somebody want editline and nothing else, that's what they import.) Finally, we'd like a module (let's call it EditReadline) whose interface coincides with the readline emulation layer of editline (ie, ). This module should use editline where it is available and otherwise readline (if that is available). We can argue about where in the hierarchy EditReadline should be located (and whether we want to call it EditReadline or something else). Following Judah's proposal, it could be System.Console.Editline.Readline (essentially following the C header structure), but it could alternatively be System.Console.EditReadline (or something else). I think it is important to make a clear distinction between these *three* interface for two reasons: * Both editline and readline have functionality that is not exposed by EditReadline (aka ). * Static linking against EditReadline is allowed for non-GPL compatible code only on systems that have editline. Manuel