these-1.2.1: An either-or-both data type.

This 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").

data These a b = This a | That b | These a b

Since version 1, this package was split into parts:

• semialign For Align and Zip type-classes.
• semialign-indexed For SemialignWithIndex class, providing ialignWith and izipWith.
• these-lens For lens combinators.
• monad-chronicle For transformers variant of These.