[Haskell-cafe] Safe Haskell and instance coherence

MigMit miguelimo38 at yandex.ru
Thu Oct 11 16:33:55 CEST 2012

On Oct 11, 2012, at 6:23 PM, Mikhail Glushenkov <the.dead.shall.rise at gmail.com> wrote:

> Hello,
> On Thu, Oct 11, 2012 at 3:54 PM, MigMit <miguelimo38 at yandex.ru> wrote:
>> 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.

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