ANNOUNCE: GHC version 6.10.1 - EditLine / terminal incompatibility?

Judah Jacobson judah.jacobson at
Fri Nov 21 19:57:27 EST 2008

On 11/21/08, Simon Marlow <marlowsd at> wrote:
> I propose we do this:
>  * extract the GHCi UI from the GHC package, put it in the ghc-bin package
>   (maybe we should rename this package to ghc-main or something).  This
>   removes the editline and bytestring (for now) dependencies from the GHC
>   package.
>  * Move to Haskeline for the default build.  We have to bring in terminfo
>   and utf8-string as bootlibs.
> This gives us line-editing on Windows, and removes problematic external C
> library dependencies.

Just so it's clear, Haskeline on POSIX does require (n)curses, an
external C library, in order to access terminfo capabilities portably.
 But in my experience curses is much more widely available by default
than readline or editline, so I still think this is a significant

>  * Make it possible to compile the ghc-bin package against readline.
>   Upload ghc-bin to Hackage, so people can say
>      cabal install ghc-bin -f readline
>   and get a GHCi built against readline if they want.  Oops - except that
>   this would mean that the ghc-main package has a variant license.  So
>   maybe we have to have a separate ghc-readline package?

That sounds reasonable.  As a side note, I'm very interested to learn
of any more issues with Haskeline that would make it less preferable
than the readline backend.


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