MLton 20210117

# MLtonMonoVector

    signature MLTON_MONO_VECTOR =
       sig
          type t
          type elem
          val fromPoly: elem vector -> t
          val toPoly: t -> elem vector
       end

- type t

  type of monomorphic vector

- type elem

  type of vector elements

- fromPoly v

  type cast a polymorphic vector to its monomorphic counterpart; in MLton, this is a constant-time operation

- toPoly v

  type cast a monomorphic vector to its polymorphic counterpart; in MLton, this is a constant-time operation