instance visibility (was: Re: The base library and GHC 6.10)

Claus Reinke claus.reinke at
Thu Sep 25 17:49:27 EDT 2008

>> I'd be interested to see a design that allows for local instances, in a
>> way that doesn't cause problems like in the URL above, but as far as I
>> know none exist yet.
> While this has come up now and then, most recently here

of course, as soon as I hit send I recalled:

    Wolfram Kahl and Kahl Scheffczyk,
    Named Instances for Haskell Type Classes

    Derek Dreyer, Robert Harper, and Manuel M. T. Chakravarty
    Modular Type Classes

while searching for those urls, I also discovered that Paul replied
to the 2001 paper in a 1992 email:

That's what I call foresight!-)


Ps. there have also been encodings of named instances, iirc.

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