I got bit by this the other day when returning a nil pointer to a struct as an error. It was incredibly frustrating when I finally figured out what was going on, and I'm curious if there's a good reason to distinguish between these 2 types of nil or if it was just an oversight/mistake during the language design process.
Go has the same complexity. From the Go spec: "For an expression x of interface type and a type T, the primary expression x.(T) asserts that x is not nil and that the value stored in x is of type T.'"
