Changes to Typeable

Simon Peyton-Jones simonpj at
Fri Oct 5 09:06:47 CEST 2012

| Does this imply forbidding user-written instances of Typeable? If yes,
| then I guess some currently accepted programs would also be rejected
| (those with manual instances)?

Yes, that's the idea; I should have said that.  Allowing users to write instances leads to potential un-soundness when doing dynamic type casts, so it has always been a Bad Idea.


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