named-sop: Dependently-typed sums and products, tagged by field name

Sums and Maps (products) indexed by a typelevel map of their field (or constructor) names and types. They can be combined and split again; their typelevel map is sorted to ensure that the end result is independent of the order you combine it in.

"Data.NamedSOP.Generic" contains functions for automatically converting between types with a Generic instance and named sums of products:

>>> data A = C { a :: Int, b :: Bool } 
>>>          | D Int Bool deriving (Generic)
>>> :t genSum (C 3 True)
NSum
 '[ "_C" ':-> NMap '[ "a" ':-> Int, "b" ':-> Bool],
    "_D" ':-> NMap '[ "_1" ':-> Int, "_2" ':-> Bool]]