Alternative.some and NonEmpty

Sven Panne svenpanne at
Mon Mar 6 08:29:02 UTC 2017

2017-03-05 13:50 GMT+01:00 Vladislav Zavialov <vlad.z.4096 at>:

> > that's solvable with CPP if needed
> Note that it's possible to avoid CPP because one can use `fmap toList
> . some` to achieve the old behavior. And the breakage is not silent,
> so it won't be too hard for maintainers.

IMHO it's basically irrelevant if you would need CPP or could do it in
plain Haskell, the main point is: It is an incompatible, breaking change
which must be acted upon by maintainers. An ongoing stream of such tiny
changes results in a non-trivial amount of work if you want to keep your
projects up-to-date.

A much better approach is to bundle such changes and discuss them, come up
with a good migration story, implement things and release them, all under a
common theme. In our case, it would be something like "use NonEmpty in base
and some central packages wherever it makes sense", *if* that is what
people want.

I'm basically neutral about the proposed change itself, but I'm -1 if it is
considered in isolation.
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