interface Empty(a:Type)
  pass
-- CHECK-NOT: Parse error

instance Empty(Int)
  pass
-- CHECK-NOT: Parse error

instance Empty(Float32)
  def witness() = 0.0
-- CHECK-NOT: Parse error
-- CHECK: Error: variable not in scope: witness

interface Inhabited(a)
  witness : a
-- CHECK-NOT: Parse error

instance Inhabited(Int)
  witness = 0
-- CHECK-NOT: Parse error

instance Inhabited(Float64)
  witness = f_to_f64(0.0)
 pass
-- CHECK: Parse error
-- CHECK: unexpected "pa"
-- CHECK: expecting end of line

instance Inhabited(Word32)
  witness = 0
   pass
-- CHECK: Parse error