Module Core_kernel__.Stable_module_types

module type S0_without_comparator : sig ... end
module type S0 : sig ... end

The polymorphic signatures require a mapping function so people can write conversion functions without either (1) re-implementing the mapping function inline or (2) reaching into the unstable part of the module.

module type S1 : sig ... end
module type S2 : sig ... end
module type S3 : sig ... end
module type S4 : sig ... end