Re: [Haskell-cafe] Safe Haskell and instance coherence

11 Oct 2012


      On Oct 11, 2012, at 6:23 PM, Mikhail Glushenkov  wrote:
...
Hello,
On Thu, Oct 11, 2012 at 3:54 PM, MigMit  wrote:
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You have a bigger problem coming. Some extensions make multiple instances OK, even in Safe Haskell. For example:
{-# LANGUAGE FlexibleInstances, IncoherentInstances, Safe #-}
[...]
Safe Haskell already disallows OverlappingInstances.
It doesn't. Overlapping instances are allowed in safe modules, provided that they won't be used in other modules.