Tour of Go, A Workthrough

Helping Beginners Get Through It

This is a workthrough of the Tour of Go, which, for better or worse, is what most recommend people do to get started in the language. The Tour is clearly not for beginner programmers and assumes coding in at least one other language (preferably C) before attempting it. It’s pedantic tone can be off-putting for many just coming to programming for the first time. This is an attempt to help assuage their their distress so they can come to realize Go is fun for beginners as well.

Video Playlist: Tour of Go, A Workthrough

Incomplete

The Tour is actually not nearly comprehensive. It is missing a lot of things that remain on the project TODO list. Given the fact that the Tour requires a JavaScript enabled browser, and that it is not really designed for beginners, this will probably remain unfinished for the foreseeable future. Check the Go resources to find other learning material to consider, but be careful, there is a lot of outdated stuff that looks like it will be there for a very long time.

Exercise: Loops and Functions

At first you just

func Sqrt(x float64) float64 {
      z := 1.0
      for i := 1; i < 10; i++ {
          z -= (z*z - x) / (2 * z)
          fmt.Println(z)
      }
      return z
  }

Then you can keep track of the difference:

func Sqrt(x float64) float64 {
      last, z := 1.0, 1.0
      for i := 1; i < 10; i++ {
          z -= (z*z - x) / (2 * z)
          delta := z - last
          fmt.Printf("z=%v delta=%v\n", z, delta)
          last = z
      }
      return z
  }

And finally remove the limit of 10 and checking for a specific delta (difference) from the last value.

package main

  import (
      "fmt"
      "math"
  )

  func Sqrt(x float64) float64 {
      last, delta, z := 1.0, 1.0, 1.0
      for delta >1e-6{
          z -= (z*z - x) / (2 * z)
          delta = math.Abs(last -z)
          //fmt.Printf("z=%v delta=%v\n", z, delta)
          last = z
      }
      return z
  }

  func main() {
      fmt.Println(Sqrt(2))
      fmt.Println(math.Sqrt(2))
  }

It looks like Go must use the value 1e-6 internally within the math.Sqrt() function.