On Mon, Feb 25, 2013 at 12:50 PM, Johannes Waldmann < [email protected]> wrote:
> Package dependencies are modelled by a relation "A depends-on B". > > Shouldn't this in fact be two relations: > API-depends-on and implementation-depends-on? > > (meaning that A API-depends-on B > iff some type of B is visible to the user of A) > > There's a third relation, A API-ABI-depends-on B iff some type of B is used in the hidden binary representation that is used in backing the API visible to A. Alexander > So what we currently have is implementation-depends-on > and API-depends-on is a sub-relation of that. > > The point being the following: assume > > * A implementation-depends-on B.1 > * not (A API-depends-on B.1), > > * U implementation-depends-on A > * U implementation-depends-on B >= 2 > > Then U (indirectly) implementation-depends > on two versions of B but it should still be safe? > (e.g., I can install B.3, re-compile U, but keep A) > > Example: A = template-haskell, B = containers > (at least I don't see any mention of Data.Map/Set in th's API, > I think the only dependency is in the implementation of PprM > > http://hackage.haskell.org/packages/archive/template-haskell/2.8.0.0/doc/html/Language-Haskell-TH-PprLib.html > ) > > or in general, A (and B.1) are baked into ghc, > but there is some B.2/B.3 out there which U wants to use. > > Or is this what already happens? (ghc would notice > that B.1.foo is different from B.2.foo. > cabal-install would warn, but proceed? > Then the effect of the proposal would just be > to switch off these warnings in some cases?) > > - J.W. > > > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe >
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