Genericize generic types

[propensive]

Rather than introduce different generic traits to represent various proto-typeclasses for converting libraries' types to a lowest-common-denominator representation, with "specific" counterparts for converting back, it might be possible to use just two:

trait Specializable:
  type Operand
  type Self
  type Domain
  def specialize(op: Operand): Self

trait Generalizable:
  type Self
  type Result
  type Domain
  def generalize(op: Self): Result

With additional definitions, such as:

erased trait Instants
erased trait Durations
erased trait Paths

we can have given instances such as, MyInstant is Generalizable across Instants into Long and MyPath is Specializable across Paths by Text.

Then, we can define general methods:

def runningTime[T: Specializable across Durations by Long]: T = T.specialize(now() - start)

or,

def load[P: Generalizable across Paths by Text](path: P): Bytes = Io.loadByFilename(P.generalize(path.s))