[Haskell-cafe] DSL in Haskell

Hi All, I was reading a Ruby book and in that it was mentioned that its capability to dynamically query and modify classes makes it suitable for implementing DSL's ... I am referring to Ruby's reflection and methods like "method_missing" here. It can allow things like not having to define constants for all possible unicode code points etc...For example, first use of U0123 could bring such a constant definition into existence etc I see multiple search hits when I look for Haskell and DSL - can someone please point me to a good primer or explain to me how equivalent of above mentioned features in Ruby can be done in Haskell ... or the Haskell alternative for it. Regards, Kashyap