Re: [Haskell] Re: Trying to install binary-0.4

17 Oct 2007


      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