exists

Existential datatypes holding evidence of constraints.

This package contains:

• Existential datatypes for holding evidence of constraints on types of kind * and * -> *;

• Type classes for existential datatypes holding evidence of constraints on types of kind * and * -> *;

• Completely useless existential datatypes holding evidence of no constraint on types of kind * and * -> *;

• Assorted type class instances for the above;

• A type-level combinator for combining constraint constructors.

(Some of these might be better off as separate packages.)

Data.Exists has most of the important things.

Minimum GHC: 7.4

Changes in 0.2:

• Removed Comonad-related things (they were probably useless anyways)

• Added Data.Exists.CPS