# exists: Existential datatypes holding evidence of constraints

[ bsd3, constraints, library ] [ Propose Tags ]

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 should maybe be split off into separate packages.

Data.Exists is the important module, the rest are peripheral.

[Index]