[Haskell] Re: Trying to install binary-0.4

[Ian Lynagh]

On Wed, Oct 17, 2007 at 01:28:45AM +0100, Duncan Coutts wrote:
> On Wed, 2007-10-17 at 00:35 +0100, Ian Lynagh wrote:
> > 
> >     package foo:
> >         module Foo where
> >             data T
> > 
> >     package bar:
> >         module Bar where
> >             bar :: T
> > 
> >     package baz:
> >         module Baz where
> >             baz :: T -> ()
> > 
> > then
> >     baz bar
> > might be a type error if I have multiple versions of foo installed and
> > bar and baz have been compiled against different versions.
> 
> Sure, those are not compatible. But we can detect that just by looking
> at the dependencies of each package.

In general it is possible to have 2 different versions of a package in a
single program, though, e.g. bar and baz could internally use different
versions of a binary-tree package.


Thanks
Ian