Utility functions for working with instructions and instruction sets.

The Data.Functor.Coproduct module is very useful with instruction sets, so this module reexports it. The Coproduct type can be used to take the union of two instruction sets, and the coproduct function can be used to construct an instruction evaluation for such an union. So if we have these two instruction evaluations:

 evalI  :: forall x. instr  x -> f x
 evalI' :: forall x. instr' x -> f x 

then their coproduct is an evaluation for the union of the instruction sets:

 coproduct evalI evalI' :: forall x. (Coproduct instr instr' x) -> f x