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

[oleg at pobox.com]

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.