fixpoint "--rewrite"


match isCons Cons x xs = (true)
match isNil  Cons x xs = (false)
match isCons Nil       = (false)
match isNil  Nil       = (true)

constant Cons : (func(1 , [@(0); [@(0)]; [@(0)]]))
constant isCons : (func(1 , [[@(0)]; bool]))
constant isNil : (func(1 , [[@(0)]; bool]))
constant Nil : (func(1 , [[@(0)]]))

expand [1 : True]

bind 1 l : {xs : [int] | true }
constraint:
  env [1]
  lhs {v:int | [isCons l && (l == Nil) ]}
  rhs {v:int | [false]}
  id 1 tag []