data LL 1 = [
  | emp { }
  | con { lHead : @(0), lTail : LL @(0) }
]

bind 0 junk : {v:LL bool | true}

constraint:
  env [0]
  lhs {v:int | true }
  rhs {v:int | emp = (if (1 < 2) then emp else (con 1 emp)) }
  id 1 tag []