ghc-dependent-sum

Dependent sum type

A dependent sum is a generalization of a particular way of thinking about the 'Either' type. 'Either a b' can be thought of as a 2-tuple '(tag, value)', where the value of the tag determines the type of the value. In particular, either 'tag = Left' and 'value :: a' or 'tag = Right' and 'value :: b'. This package allows you to define your own dependent sum types by using your own "tag" types.