libghc-these-doc binary package in Ubuntu Focal amd64

 Package provides a data type `These a b' which can hold a value of either
 type or values of each type. This is usually thought of as an "inclusive or"
 type (contrasting `Either a b' as "exclusive or") or as an "outer join" type
 (contrasting `(a, b)' as "inner join").
 .
 The major use case of this is provided by the Align class, representing a
 generalized notion of "zipping with padding" that combines structures without
 truncating to the size of the smaller input.
 .
 Also included is ChronicleT, a monad transformer based on the Monad instance
 for `These a', along with the usual monad transformer bells and whistles.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.

Source package