[Haskell-cafe] MPTC and type classes issue (polymorphic '+')

[Joel Reymont]

On Apr 7, 2007, at 4:16 PM, Stefan O'Rear wrote:

> You can probably use -fallow-incoherent-instances for this.  It has a
> scary name on purpose since it doesn't usually do what you think it
> should...  My (very limited!) understanding of type checking
> algorithms says that in this case, the worst that can fail is an extra
> call to fromInteger :: Integer -> Integer.  Big deal.

It only works until I add instance declarations for Fractional.

	Thanks, Joel

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