Very thorough, perhaps to a fault, this book is probably a great second read for most Go newcomers.

Last week Go 1.20 was released! It did include a few changes to the Go spec, but none of them affect the portions we’ve covered so far in this series, so we’ll just continue on our merry way… Variables A variable is a storage location for holding a value. The set of permissible values is determined by the variable’s type. A variable declaration or, for function parameters and results, the signature of a function declaration or function literal reserves storage for a named variable.

A bonus review of this early-access book, which I'm quite excited about.

Constants … Constants may be typed or untyped. Now that’s interesting. And powerful. This is one of the features of Go I featured in my recent video 10 Reasons I Like Go. This feature really helps bridge the gap between the convenience of dynamically typed languages, and the safety of statically typed languages. Let’s look at the details… Literal constants, true, false, iota, and certain constant expressions containing only untyped constant operands are untyped.

This well-written, quick intro to Go for professional developers has some really strong points, but some important down sides, too.

Constants … Numeric constants represent exact values of arbitrary precision and do not overflow. Consequently, there are no constants denoting the IEEE-754 negative zero, infinity, and not-a-number values. Now this is a very interesting thing about constants in Go, and it’s something that confuses a lot of people. So let’s play around with this one a bit. If you’re experienced with compiled languages, you’re probably already familiar with numeric overflows.

Very well organized, reasonable content, but the rampant grammatical errors are terribly distracting.

Yesterday I made a passing comment in the last code example: Although x is not a constant, the result of len(x) is, because it is known at compile time. I want to dive into this aspect of constants in Go today. In Go (or at least most, if not all implementations of Go) a constant is logically replaced during compilation. This can be a useful mental shortcut when trying to determine whether a given expression can be a constant or not.

Full of factual errors, poorly edited, poorly organized. All around a bad book.

Constants There are boolean constants, rune constants, integer constants, floating-point constants, complex constants, and string constants. Rune, integer, floating-point, and complex constants are collectively called numeric constants. So there we have it. A comprehensive list of the available constant types in Go. And all but boolean and string constants are numeric. Notice that none of the composite types can be constants in Go. You can’t have a constant array, slice, struct, or interface.

"The focus for Learning Go isn't just how to write programs in Go; it's how to write Go idiomatically."