[Haskell-cafe] OSX, ghci, dylib, what is the correct way?

[Jason Dagit]

On Sun, Jun 12, 2011 at 11:45 AM, Brandon Allbery <allbery.b at gmail.com> wrote:
> On Sun, Jun 12, 2011 at 14:31, Jason Dagit <dagitj at gmail.com> wrote:
>> If I build the C library as a .a, then ghci comlains that it cannot
>> open the .dylib.  My first question is: Why does ghci need a .dylib
>> and does it really use it?
>
> Static libraries are... static.  ghci would have to rebuild itself
> against the static archive to use it; that's how static archives work.
>  Dynamic libraries are dynamic because they can be loaded at runtime
> instead of compile time.

Interesting.  When I use dtruss to see what files ghci opens, it
definitely opens .a files.  That gave me the impression it knows how
to open a .a and use it at run-time.

>> When I build a dylib I get a [segfault when loading the code into ghci][2].
>
> I believe ghci still uses its own dynamic loader instead of the
> standard library one, and as such it doesn't handle everything quite
> correctly; Mach-O is a moving target and Apple doesn't always document
> its changes.[1]  When you compile, the system linker is used to build
> the executable and things work properly.
>
> [1] http://hackage.haskell.org/trac/ghc/ticket/4244
>

It's hard for me to make sense of that ticket with so little context.
This comment seems to go against what you're saying:
Changed 10 months ago by igloo

milestone set to 6.16.1
The best way to achieve this is probably to switch to using dynamic
libraries for GHCi.

Thanks,
Jason