[Haskell-cafe] Re: Hmm, what license to use?

Simon Marlow marlowsd at gmail.com
Fri Oct 3 11:50:52 EDT 2008

Magnus Therning wrote:
> On Fri, Oct 3, 2008 at 12:59 PM, Simon Marlow <simonmarhaskell at gmail.com> wrote:
>> Magnus Therning wrote:
>>> On Wed, Oct 1, 2008 at 6:03 PM, Simon Marlow <simonmarhaskell at gmail.com>
>>> wrote:
>>> [..]
>>>> Dynamic linking doesn't solve all the problems, we still have the problem
>>>> that GHC does a lot of cross-module inlining, regardless of whether
>>>> dynamic
>>>> linking is used.  However, I really would like to have a way to have
>>>> complete control over what is exposed across a package boundary.  We need
>>>> this not just for licensing reasons, but also for making a dynamic
>>>> library
>>>> with a fixed ABI, so it can be upgraded later.
>>> I have a really hard time following this.  Are you seriously saying
>>> that GHC is inlining code from modules _and_ link dynamically at the
>>> same time.  That seems like a remarkably strange thing to do, or maybe
>>> I'm just missing something.
>> That's exactly what would happen, if we shipped dynamic linking support with
>> GHC as it stands.  It's just a linking mechanism, an alternative to static
>> linking, and has no impact on the amount or nature of inter-module
>> optimisation that GHC does.
> Ah, now I understand.  The object for GHC would be to reduce the
> system-wide use of memory rather than substitutability of DLLs then,
> right?
> Why would it be interesting to have sharable objects without substitutability?

It'll make our binary distributions a lot smaller for one thing.  Also, the 
on-disk size of binaries will be a lot smaller - this is something you 
notice if you run a GHC test suite, for example.

Also, the GHCi binary contains the base package, but loads up another 
complete copy when it starts up.  And if you load up the GHC package inside 
GHCi, then you have two complete copies of GHC in memory.  Dynamic linking 
fixes all this.


More information about the Haskell-Cafe mailing list