ghc-typelits-knownnat

A type checker plugin for GHC that can derive "complex" KnownNat constraints from other simple/variable KnownNat constraints. i.e. without this plugin, you must have both a KnownNat n and a KnownNat (n+2) constraint in the type signature of the following function: Using the plugin you can omit the KnownNat (n+2) constraint: The plugin can derive KnownNat constraints for types consisting of: Type variables, when there is a corresponding KnownNat constraint Type-level naturals Applications of the arithmetic expression: +,-,*,^ Type functions, when there is either: a matching given KnownNat constraint; or a corresponding KnownNat<N> instance for the type function To use the plugin, add the Pragma to the header of your file.