[Haskell-cafe] expression problem

[Patrick Browne]

Hi,
The expression problem [1] can be described as the ability to add new
variants (either constructors or methods) to a data type  without
changing the existing code. The Haskell and OO language issues are well
described at [1]
It seems that the expression problem does not exist in Maude[2].

My question is:
Using basic and easy parts of the Haskell, does Haskell currently handle
the expression problem.  In other words I would like to avoid demanding
and sophisticated coding techniques or non-standard Haskell extensions
(i.e. it should be easy for the average programmer to use).
If there is a simple solution could you please point me to an example.

Thanks,
Pat



[1] Dr. Ralf Laemmel
http://channel9.msdn.com/shows/Going+Deep/C9-Lectures-Dr-Ralf-Laemmel-Advanced-Functional-Programming-The-Expression-Problem/
[2]http://lists.cs.uiuc.edu/pipermail/maude-help/2010-January/000336.html


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