Straight from the tutorial: "Since the switch value is just true, we could leave it off—as is also the situation in a for statement, a missing value means true

Straight from the tutorial: "Since the switch value is just true, we could leave it off—as is also the situation in a for statement, a missing value means true. In fact, such a switch is a form of if-else chain. While we're here, it should be mentioned that in switch statements each case has an implicit break." The basic outcome is that: 1. The assignment to er, nr is an initialization statement for the switch. 2. The true (default value if not specified) is used to configure the switch as an if-else chain which is required as the assignment above makes the purpose of the switch ambiguous (is the result of the assignment configuring the switch - how do you do that as multiple values are returned?). You could rewrite it: nr, er := f.Read(buf[:]); switch true { ... } or even: nr, er := f.Read(buf[:]); switch { ... } But the switch initializer scopes it to the switch block cleanly.