My jump into golang (notes)


I’m learning Go, as one of my latest projects involve doing code review on a code base written in it. A very interesting language, with a lot of similarities to other languages I’ve worked with, like Python, JavaScript and C.

I’m taking “A Tour of Go”, and taking notes as I go. This post will probably grow over time. The tour itself is warmly recommended. A very nice way to learn a new programming language.

Random notes

fmt.Fprintln(os.Stderr, err)

Implement custom errors

type ErrNegativeSqrt float64

func (e ErrNegativeSqrt) Error() string {
    return fmt.Sprintf("Cannot Sqrt negative number: %f", e)

func Sqrt(x float64) (float64, error) {
    if x < 0 {
        return 0, ErrNegativeSqrt(x)
    return 0, nil


func Rot13Decode(encoded []byte) []byte {
    decoded := make([]byte, len(encoded))
    for i, b := range encoded {
        switch true {
        case b >  0x6D: // m
            decoded[i] = b - 13
        case b >= 0x61: // a
            decoded[i] = b + 13
        case b >  0x4D: // M
            decoded[i] = b - 13
        case b >= 0x41: // A
            decoded[i] = b + 13
    return decoded


If you have any comments or feedback, please send me an e-mail. (stig at stigok dotcom)