Tour of GO Error exercise

handle_errors.go

package main

import (
	"fmt"
)

type ErrNegativeSqrt float64

func (e ErrNegativeSqrt) Error() string {
	return fmt.Sprint("Can't Sqrt negative number: ", float64(e))
}

func Sqrt(x float64) (float64, error) {
	z := 1.0
	
	if x < 0 {
		return z, ErrNegativeSqrt(x)
	}

	for i := 0; i < 10; i++ {
		z -= (z*z - x) / (2 * z)
	}

	return z, nil
}

func main() {
	fmt.Println(Sqrt(2))
	fmt.Println(Sqrt(-3))
}