[_ezkx]

I think this is right, but it's still IMO basically a natural language semantics issue. For instance in haskell (which has a pretty advanced static type system), I would still probably be satisfied with:

  -- A float between 0 and 1, inclusive.
  type UnitInterval = Float
  
  foo :: UnitInterval -> SomeResultPresumably
  foo accuracy = ...

i.e. I think the essential problem in the SO question is solved, even though we have no additional type safety.

A language without type synonyms could do just as well with CPP defines