gistfile1.txt

Object -- Unary 1; the root trait, very first one created; 1 is its "tag"
Foo = Object clone -- Union (Unary 2) (Unary 1) (@clone might become @derive or something)
Bar = Foo clone -- Union (Unary 3) (Union (Unary 2) (Unary 1))
Fizz = Foo clone -- Union (Unary 4) (Union (Unary 2) (Unary 1))

-- defines on trait:
--   Intersection (Unary 2) (Unary 3)
-- note that the unions are gone; it only intersects on the "heads"
(f: Foo) x: (b: Bar) := 1

-- searches for trait:
--   Intersection (Union (Unary 2) (Unary 1)) (Union (Unary 3) (Union (Unary 2) (Unary 1)))
-- ie, any trait in unions can match
Foo x: Bar
  => 1

-- also finds @x: because Unary 2 is in Fizz's union
-- Bar x: Bar would work too
Fizz x: Bar
  => 1