This page is not a coherent topic, just a list of things i saw from the Haskell community that i want to read or think about sometime:
haskell open data syb
http://www.haskell.org/haskellwiki/Extensible_datatypes
http://okmij.org/ftp/Haskell/generics.html
http://stackoverflow.com/questions/870919/why-are-haskell-algebraic-data-types-closed
http://www.cs.ucla.edu/~todd/research/pub.php?id=icfp02
http://stackoverflow.com/a/871002
http://stackoverflow.com/a/871375
http://www.haskell.org/haskellwiki/Extensible%5Fdatatypes
http://lambda-the-ultimate.org/node/1453
http://en.wikipedia.org/wiki/Expression_problem
http://lambda-the-ultimate.org/node/3600
http://www.citeulike.org/user/AndreasSchropp/article/1023768
Software extension and integration with type classes
http://www.informatik.uni-marburg.de/~kos/papers/gpce06.pdf
ohaskell
https://www.google.com/search?q=scfap+yur+boilerplate&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official#q=scrap+your+boilerplate+oleg&rls=org.mozilla:en-US:official https://www.google.com/search?q=scfap+yur+boilerplate&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official#q=scrap+your+boilerplate+oleg+o%27haskell&rls=org.mozilla:en-US:official
http://www.haskell.org/pipermail/generics/2006-October/000034.html
http://www.haskellforall.com/2012/05/scrap-your-type-classes.html http://www.reddit.com/r/haskell/comments/t2yy2/scrap_your_type_classes/
https://userpages.uni-koblenz.de/~laemmel/TheEagle/resources/pdf/xproblem2.pdf