My Dictionary

my_dict.go

package main

import (
    "errors"
    "fmt"
)

type KeyPair  struct{
  key string
  value string
}

type MyDict []KeyPair


func(dict MyDict) IndexOf(key string) int {

  for i, value := range dict{
      if value.key == key {
        return i
      }
  }

  return -1
}

func (dict MyDict) Exists(key string) bool {
  return dict.IndexOf(key) != -1
}

func (dict MyDict) Insert(key string, value string) (MyDict, error) {
    if dict.Exists(key) {
      return nil, errors.New("Key already exists")
    }

    dict = append(dict, KeyPair{
      key: key,
      value: value,
    })

    return dict, nil
}

func main(){
    d := MyDict{}

    d, err := d.Insert("hello", "world")
    d, err = d.Insert("hello2", "world2")
    d, err = d.Insert("hello2", "world2")

    if err == nil{
      fmt.Println("Duplicated key it should have failed")
    } else {
        fmt.Println("All Good")
        fmt.Println(d)
    }


}