[Haskell-cafe] is closing a class this easy?

Wolfgang Jeltsch g9ks157k at acme.softbase.org
Sat Jul 18 08:49:14 EDT 2009

Am Samstag, 18. Juli 2009 08:58 schrieb Miguel Mitrofanov:
> Oops... Sorry, wrong line. Should be
> isAB :: forall p. p A -> p B -> p x

Is this a well-known approach for closing classes?

I came across the same idea and implemented a generic framework for closing 
classes in this way. I did this to simulate algebraic data kinds and kind 
polymorphism over such kinds. I needed this for the record system of 
Grapefruit. The code is here:


Explaination of the techniques used in this code will probably follow as part 
of an IFL 2009 paper.

Now I wonder which of my ideas are actually new and which are just old hat. 
Could you maybe answer this question?

Best wishes,

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