Re: [Haskell-cafe] Efficient object identity (aka symbols as data)

On Thu, May 26, 2011 at 04:45, Jacek Generowicz wrote:

What is the Haskell approach to efficient comparison and lookup of objects by their identity?

ghc uses Data.Unique to generate unique internal identifiers to associate with things. (Think gensym. Hm, except last time I did anything serious with Lisp, it was Maclisp... does gensym even still exist, or did CL do something inscrutable with it?) Beyond that, the existence of functions such as reallyUnsafePointerEquality# makes me think it's a Hard Problem.