Syntax Error: Non-declaration statement outside function body

The function makeEvenGenerator is supposed to return a function that generates even numbers in a sequential manner:

package main 
import "fmt"
func makeEvenGenerator() func() uint {
	i := uint(0)
	return func() (ret uint) {
		ret = i
		i += 2
		return
	}
}func main() {
	nextEven := makeEvenGenerator()
	fmt.Println(nextEven()) // 0
	fmt.Println(nextEven()) // 2
	fmt.Println(nextEven()) // 4
}  

When I run it, I get the error syntax error: unexpected func, expecting semicolon or newline and Non-declaration statement outside function body.

The code is taken verbatim from An Introduction to Programming in Go by Caleb Doxsey. I am not sure what the problem is.

You are missing a newline between the "}" at the end of the makeEvenGenerator and the "func" in main.

I fixed the error and posted the code to the playground.

There are rules about semicolons.

> The Go Programming Language Specification
>
> Semicolons
>
> The formal grammar uses semicolons ";" as terminators in a number of
> productions. Go programs may omit most of these semicolons using the
> following two rules:
>
> 1. When the input is broken into tokens, a semicolon is automatically inserted into the token stream at the end of a non-blank line if the
> line's final token is
> an identifier
> an integer, floating-point, imaginary, rune, or string literal
> one of the keywords break, continue, fallthrough, or return
> one of the operators and delimiters ++, --, ), ], or }
> 2. To allow complex statements to occupy a single line, a semicolon may be omitted before a closing ")" or "}".

The error is here,

}func main() {

Write,

}
func main() {

You were missing a new line between } at the end of makeEvenGenerator and func main.

Also an alternative approach for that pattern is to use a channel not return a function:

func evenGenerator() <-chan uint {
	ch := make(chan uint)
	go func() {
		i := uint(0)
		for {
			ch <- i
			i += 2
		}
	}()
	return ch
}
func main() {
	evens := evenGenerator()
	for i := 0; i < 3; i++ {
		fmt.Println(<-evens)
	}
}

<kbd>playground</kbd>