default instance for IsString

Erik Hesselink hesselink at
Tue Apr 24 10:36:10 CEST 2012

On Tue, Apr 24, 2012 at 08:32, Michael Snoyman <michael at> wrote:
> Here's a theoretically simple solution to the problem. How about
> adding a new method to the IsString typeclass:
>    isValidString :: String -> Bool

If you're going with this approach, why not evaluate the conversion
from String immediately? For either case you have to know the
monomorphic type, and converting at compile time is more efficient as
well. But we're getting pretty close to Template Haskell here.


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