Go函数声明语法

Question

I have just started to learn Go language and still trying to digest few things.

I wrote a function add as:

func add(a int, b int) int {
  return a + b
}
// works fine

func add(a, b) int {
  return a + b
}
// ./hello.go:7: undefined: a
// ./hello.go:7: undefined: b
// Digested: May be I need to give type

func add(a, b int) int {
  return a + b
}
// works fine interestingly 

func add(a int, b) int {
  return a + b
}
// ./hello.go:7: final function parameter must have type

I am really confused or due to lack of knowledge unable to understand the use case of

final function parameter must have type.

Answer 1

I mentioned the IdentifierList in "Can you declare multiple variables at once in Go?": that explains a, b int.

But you need to have a type associated to each parameters of a function, which is not the case in the last int a, b parameter list.

The order is always var type, not type var, following the variable declaration spec:

 VarSpec     = IdentifierList ( Type  [ "=" ExpressionList ] | "=" ExpressionList ) .

You would always find a type after an IdentifierList: a int or a, b int