[#250] Reexport `group`-like functions from `Data.List.NonEmpty`

[DK318]

Description

Problem

At this moment group function returns [[a]] instead of [NonEmpty a]. Often returning list of lists is unsafe.

Solution

Replace group export from Data.List with group, groupBy, groupWith and groupAllWith from Data.List.NonEmpty.

Related issues(s)

• Fixes #250

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[gromakovsky]

Btw, there are 2 more functions in Data.List.NonEmpty I would consider exporting:

• groupWith
• groupAllWith

From my experience, the former might be even more useful than groupBy. You often need to compare by some field and doing groupWith field is more convenient than groupBy (\a b -> field a < field b). The latter is great because it sorts elements. There were a number of times when I made a bug because I (wrongly) expected grouping of all items by group function. Before I discovered groupAllWith, I had to do sorting myself a few times.