register-machine-typelevel (hackage): Computationally universal register machine implementation at the type-level. This formulation is identical to the Lambek machine, with the addition of an explicit Halt instruction, for convenience. This means (or rather, this is made possible by the fact) that that Haskell's type system is Turing complete (at least with TypeFamilies and UndecidableInstances).
Keywords: bsd3|language|library