// test is an existential data type 
//  data Test a b = Test {forall z. z}
// @(2) is not bound by the two top variables

data Test 2 = [
       | test { vtest : func(1 , [@(2)])}
     ]

bind 0 f : {v:int | true}
bind 1 g : {v:int | true}

constraint:
  env [0; 1]
  lhs {v:int | test f = test g }
  rhs {v:int | f = g }
  id 1 tag []