Proposal: Add --with-libedit flag to the readline package

[kahl at cas.mcmaster.ca]

Judah Jacobson" <judah.jacobson at gmail.com> wrote:
 > 
 > It would be useful for the readline package to support compiling
 > against the libedit library (which provides a subset of the readline
 > APIs):
 > 
 >  - libedit is available by default on OS X.
 >  - since libedit is BSD-licensed, there are no problems statically
 > linking ghc with it. (This may be useful on Windows.)
 > 
 > I propose adding a --with-libedit flag to the readline autoconf
 > script. Without that flag, the package will behave exactly as before,
 > refusing to link against libedit. With that flag, the following
 > behavior occurs:
 > 
 >  - GNUreadline.framework (OS X - only) is ignored, if present
 >  - We try to link with -lreadline, and don't fail if readline is
 > actually libedit.
 >  - If it is libedit, we #ifdef out all of the functions not supported
 > by libedit. (these are generally low-level APIs not needed by most
 > applications, including ghci.) Otherwise, if we're linking against GNU
 > readline, we support all the available APIs.

In my opinion,
a flag with these effects should be called ``--allow-libedit''.


For the flag ``--with-libedit'' I would expect:

  - We try to link with -ledit first.

  - Only if that fails, we try whether we can get libedit via -lreadline.

  - If we cannot get libedit, we fail.

This makes it easier to produce libedit-linked binaries on systems
that do have libreadline.


Wolfram