[Haskell-cafe] Can't cabal install readline

[Judah Jacobson]

On Fri, Dec 5, 2008 at 1:10 PM, Martijn van Steenbergen
<martijn at van.steenbergen.nl> wrote:
> Hello,
>
> This week I upgraded to GHC 6.10 using the .pkg installer. It installed
> without a single hiccup -- thanks!
>
> I've noticed two odd things: the standard library haddock that comes with
> the installer doesn't have links to the hs-coloured sources anymore (and
> neither does the online documentation); I miss that a lot. I also can't
> Ctrl+R anymore in GHCi to search my command history. But I can learn to live
> without those.

The following instructions should re-enable Ctrl-R:

http://mult.ifario.us/p/editrc-tidbit-for-ghci

> Another minor inconvenience is that the packages I had installed (using
>  cabal) are no longer available to GHC -- I think I will have to reinstall
> them. But I cannot continue working on my Yogurt project anymore, because it
> depends on readline, which fails to build:
>
> <snip>
> checking for rl_readline_version... yes
> checking for rl_begin_undo_group... no
> configure: error: readline not found, so this package cannot be built
> See `config.log' for more details.
> cabal: Error: some packages failed to install:
> Yogurt-0.2 depends on readline-1.0.1.0 which failed to install.
> readline-1.0.1.0 failed during the configure step. The exception was:
> exit: ExitFailure 1


The above happens because GHC is using the OS X default installation
of libreadline.a which is actually a link to libedit that doesn't
implement the full readline API.

If you already have the MacPorts readline, you just need to tell cabal
where it is, with (for example)

cabal install readline --extra-include-dirs=/opt/local/include
--extra-lib-dirs=/opt/local/lib

-Judah