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