editline vs haskeline (was: 6.10-candidate tested)

Claus Reinke claus.reinke at talk21.com
Wed Sep 24 17:34:16 EDT 2008

>> Would it be possible to use haskeline as a fallback/default,
>> for future Ghc's?
>> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskeline
> As the author of haskeline, integrating it into ghc is on my TODO
> list. :-) 

Good to hear!-)

> Note that the earliest this could happen would be
> ghc-6.12.1, which won't be released for at least another year.

Why that? It wouldn't change any APIs, and if you're afraid of
changing client programs that use ghci (is that likely? is the key set
different from editline? and for windows, you'd only be adding 
line editing functionality, not removing/changing any), you can
always put it behind an option.

Or is the API so different that you'd have to rewrite ghci? There
shouldn't be more than a handful locations affected, iirc, but they
are all tuned to readline/editline's imperative API.

> But just to reiterate:
> 1) Other than on Windows, libedit is widely available and compatible
> (including Debian, which just needs the libedit-dev package).
> 2) The Windows console provides basic interaction even without
> libedit, including arrow key left/right, history, delete key, etc.
> (Tab completion of Haskell identifiers is the most glaring omission.)

I don't mind whether it is editline or haskeline, but as a windows 
user, I'd like to have ghci's tab completion (it isn't limited to identifiers, 
either, I think) - ever since adding support for various Haskell-related 
completions in my Vim editing, I miss it when using ghci.. rlwrap is
ok, but no proper replacement.


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