Type Families and defaults

Simon Peyton-Jones simonpj at microsoft.com
Wed Sep 8 03:55:30 EDT 2010


I'm afraid I didn't understand your questions well enough to answer them.  But it'd be worth reading http://www.haskell.org/ghc/docs/6.12.2/html/users_guide/other-type-extensions.html#scoped-type-variables

| > It's not trivial to add, but not really hard either.  Has anyone else been
| bitten by this?
| It would be great if it would be added. Obviously I am for it. ;-)
| I think n should be scoped for the whole the class definition,
| everywhere, not just parameter and return values types. If somebody
| would define the same name for it for some local definition, GHC
| should make a "shadowing a variable" warning.

I do rather agree. Let's see if others do.


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