RowList operations

[LiamGoodacre]

Building up a collection of RowList operations. PR for discussion.

[MonoidMusician]

Do you want to add a UnionNub kind of thing for properly typing merge? (as in RowUnion.purs, which should be left-biased unique but only has a Union constraint which creates duplicates)

Here's a naïve implementation (left-biased):

class UnionNub
  (a :: # Type)
  (b :: # Type)
  (c :: # Type)
  | -> a b c
instance unionNub ::
  ( Union a b r
  , RowToList r rl
  , ListToRow rl r
  , RowListNub rl cl
  , ListToRow cl c
  ) => UnionNub a b c

I could probably draft up intersection and difference too.

[justinwoo]

Could this go in sometime so I can depend on it? 😄 I need to use the RowAppend class the most

[paf31]

I'm happy to merge this whenever @LiamGoodacre says it's good to go.

[LiamGoodacre]

Sorry, I completely forgot about this.

[LiamGoodacre]

I'll merge once Travis is happy.

[LiamGoodacre]

@paf31 do you want to make a v2.4.1 for this?