proposal #4095: add Applicative instance for Either
qdunkan at gmail.com
Tue Jun 1 14:09:44 EDT 2010
On Tue, Jun 1, 2010 at 8:14 AM, Yitzchak Gale <gale at sefer.org> wrote:
> Iavor Diatchki wrote:
>> Are there any uses of this instance that are not related to error
> Yes, in fact, exception handling is a minor corner case.
> The Either Monad/Applicative provides multi-level exit
> from nested complex computations. That effect is
> provided in a much more complicated way by callCC
> in CPS, but the straightforward way is with Either.
Can you give a specific example? I'm trying to think of how this is
different from the normal exceptional escape mechanism.
I use Either as a Maybe + info all the time, but I think you're
talking about something more sophisticated here.
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