@hackage ghc-typelits-natnormalise0.8.0

A type checker plugin for GHC that can solve equalities and inequalities of types of kind Nat, where these types are either: . * Type-level naturals . * Type variables . * Applications of the arithmetic expressions (+,-,*,^). . It solves these equalities by normalising them to sort-of SOP (Sum-of-Products) form, and then perform a simple syntactic equality. . For example, this solver can prove the equality between: . (x + 2)^(y + 2) . and . 4*x*(2 + x)^y + 4*(2 + x)^y + (2 + x)^y*x^2 . Because the latter is actually the SOP normal form of the former. . To use the plugin, add the . OPTIONS_GHC -fplugin GHC.TypeLits.Normalise . Pragma to the header of your file.