Top-level Variable Declarations

At the top level, use the standard var keyword. Do not specify the type,unless it is not the same type as the expression.

var _s string = F()
 
func F() string { return "A" }

var _s = F()
// Since F already states that it returns a string, we don't need to specify
// the type again.
 
func F() string { return "A" }

Specify the type if the type of the expression does not match the desired typeexactly.

type myError struct{}
 
func (myError) Error() string { return "error" }
 
func F() myError { return myError{} }
 
var _e error = F()
// F returns an object of type myError but we want error.