[Haskell-cafe] Why Maybe exists if there is Either?

Brandon Allbery allbery.b at gmail.com
Thu Jan 9 17:12:52 UTC 2014

On Thu, Jan 9, 2014 at 11:52 AM, Vlatko Basic <vlatko.basic at gmail.com>wrote:

> > ... what exactly is the problem with using appropriate data types in
> appropriate places ...
> It is a good thing. Very good. But I do not think all library writers are
> using it in correct places. But that's another problem.

In Haskell it's even a solved one: use an appropriate typeclass. We have
several error-like typeclasses. Admittedly, if some library does not take
advantage of this your recourse may be to submit a patch.

And you still seem to be fixated on the notion that Maybe is only for
errors. What exactly is the error in "user did not provide an optional

brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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