default instance for IsString
twhitehead at gmail.com
Thu Apr 26 00:04:33 CEST 2012
On April 25, 2012 12:20:16 Johan Tibell wrote:
> On Wed, Apr 25, 2012 at 8:19 AM, Tyson Whitehead <twhitehead at gmail.com>
> > Is there a technical reason this couldn't be done? The Haskell report
> > only says doing this is not part of haskell. It doesn't say why.
> I think the problem is incoherence, what if the same Map value got
> used with two different instances of Int?
I'm not sure I follow how allowing control over importing of instances could
allow a programmer to define multiple instances for the same types.
I would have expected this to result in a link time error as a product of
multiple declerations (something like a multiple symbol definition) regardless
of whether any module brings it into scope as a possible candidate for use.
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