Currently derivation of generators with dependent types is supported, e.g.

gf : Fuel -> (n : Nat) -> Gen MaybeEmpty $ Fin n
gf = deriveGen

But derivation of generators for data types that are polymophic over types is not.
E.g., this does not work:

gl : Fuel -> (a : Type) -> (Fuel -> Gen MaybeEmpty a) => Gen MaybeEmpty $ List a
gl = deriveGen

The whole task can be divided to at least these subtasks:

• Support for non-higher kinded given type arguments in covariant positions
• Preferring given type arguments in the ordering in the least-effort constructor derivator in covariant positions
• Support for non-higher kinded generated type arguments
• Support for higher-kinded type arguments
• Support for type arguments in the contravariant positions