[Haskell-cafe] checking types with type families

Claus Reinke claus.reinke at talk21.com
Wed Jun 23 04:28:59 EDT 2010

> I'm interested in situations where you think fundeps work 
> and type families don't.  Reason: no one knows how to make 
> fundeps work cleanly with local type constraints (such as GADTs).  
> If you think you have such as case, do send me a test case.  

Do you have a wiki page somewhere collecting these examples?
I seem to recall that similar discussions have arisen before and
test cases have been provided but I wouldn't know where to 
check for the currently recorded state of differences.

Also, what is the difference between fundeps and type families
wrt local type constraints? I had always assumed them to be
equivalent, if fully implemented. Similar to logic vs functional
programming, where Haskellers tend to find the latter more 
convenient. Functional logic programming shows that there 
are some tricks missing if one just drops the logic part.



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