[Haskell-cafe] Re: Has anyone looked into adding subtyping to Haskell?

Polymorphic extensible records with subtyping are already expressible in Haskell. There is nothing needs to be added: http://homepages.cwi.nl/~ralf/HList/ http://homepages.cwi.nl/~ralf/OOHaskell/ The full code is available via darcs http://darcs.haskell.org/OOHaskell/ As to polymorphic variants, they too are implementable in Haskell right now. No new extensions are required. http://www.haskell.org/pipermail/haskell/2006-July/018172.html http://darcs.haskell.org/HList/src/VariantP.hs The code shows that the expression problem is solved in Haskell as it is.