emptyTypeAscription.lean:3:19-3:24: error(lean.invalidDottedIdent): Invalid dotted identifier notation: The expected type of `.zero` could not be determined

Hint: Using one of these would be unambiguous:
  [apply] `BitVec.zero`
  [apply] `Dyadic.zero`
  [apply] `Nat.zero`
  [apply] `Vector.zero`
  [apply] `Zero.zero`
  [apply] `System.Uri.UriEscape.zero`
  [apply] `Lean.Grind.IntModule.OfNatModule.zero`
  [apply] `Lean.Grind.Linarith.Expr.zero`
emptyTypeAscription.lean:4:29-4:34: error(lean.invalidDottedIdent): Invalid dotted identifier notation: The expected type of `.zero` could not be determined

Hint: Using one of these would be unambiguous:
  [apply] `BitVec.zero`
  [apply] `Dyadic.zero`
  [apply] `Nat.zero`
  [apply] `Vector.zero`
  [apply] `Zero.zero`
  [apply] `System.Uri.UriEscape.zero`
  [apply] `Lean.Grind.IntModule.OfNatModule.zero`
  [apply] `Lean.Grind.Linarith.Expr.zero`
emptyTypeAscription.lean:9:63-9:70: error: invalid `▸` notation, expected result type of cast is 
  w = add x y
however, the equality 
  h₁
of type 
  z = x + y
does not contain the expected result type on either the left or the right hand side
emptyTypeAscription.lean:10:55-10:62: error: invalid `▸` notation, expected result type of cast is 
  w = add x y
however, the equality 
  h₁
of type 
  z = x + y
does not contain the expected result type on either the left or the right hand side