Chatbot 2: Improve the chatbot with a memory

Many people can recount their first memory. We don’t really know how we do it, or why it is a first memory. It’s just there. We can also remember things more recently – or – remember information that is imaginary. For this lesson, we will be covering memory in terms of programming. Because a chatbot without a history, is like playing Memory and just choosing random cards each turn. Lesson examples can be found on Github

Step 1: Understanding the Lesson

Before we dig into code – let’s see if we can understand a little more about storing things in program memory. For most languages a developer can write, there are a few different ways to store data. In previous lessons, we’ve covered what a variable is – including a few types of variables. In this lesson, we are diving more deeply into the array type of variable.

One way to understand an array, is to think of series of mailboxes. They all have a number on them so the delivery person can put the mail into the correct slot. When a large neighborhood is built, there are only so many houses – and – there are only so many mailboxes. Depending on how this neighborhood is setup, any new houses will either be an easy addition (or) for a grouped mailbox setup – a new group would eventually need to be created. Arrays are like the grouped mailbox setup.

But what is an array, really? An array is a declared list of keys and values. From the mailbox example, the mailbox number is the key, and the things inside the mailbox are the value. At a more physical layer – arrays are blocks of ram reserved for storing sets of specific types of variables. In different programming languages, there are different mechanics for using arrays. In c++, one needs to program what happens if you try to add more keys to an array then the original requested amount. In golang – the language itself handles this for you using slices – so you don’t have to program the tedious memory management. Most modern languages handle the array management operations in some similar fashion.

Step 2: Using an Array in Golang

Now that we’ve briefly covered the definition of an array, let’s look at a few array operations. The Golang Tour provides an example of arrays here: A Tour of Go (golang.org).

Example from the golang tour with notes:

func main() {
  // creating a new array
  var a [2]string

  // adding to an array using a key
  a[0] = "Hello"
  a[1] = "World"

  // looking up something in an array
  fmt.Println(a[0], a[1]) // Prints Hello World

  // Creating an array with values
  primes := [6]int{2, 3, 5, 7, 11, 13}
  fmt.Println(primes) // Print [2 3 5 7 11 13]

  // removing the item with key 3 from the array
  var slice []int                                // create a 
  slice - notice how it doesn't have a length specified?
  slice = append(slice, 1, 2, 3, 4, 5, 6) // add values 
  to the array
  removalKey := 3                                       // set a key for removal

  // remove an item by adding the first portion (before the key, and the second half after the key together) 
  slice = append(slice[:removalKey], 
  slice[removalKey+1:]...)
  fmt.Println(slice) // Print [1 2 3 5 6]        // notice how the '4' is gone?

  // iterate (loop) through the slice and print the key and the value
  for key, value := range slice {
    fmt.Println(k, v)
  } 
}

Step 3: Chatbot wants a slice

With only a few lines of change, we are going to have chatbot keep a short term memory of the conversation. Here is a breakdown of the logic we’re going to use for chatbot:

1. launch program
2. send a friendly greeting
3. send a simple instruction
4. Have the user put something in
5. echo what the user put in
6. Check if the user typed ‘history’
   1. Loop through the history slice
   2. print the key and the value
7. repeat 4-6 until the user says ‘bye’

To start, we will initialize a new slice.

// Slice for storing the history of the world.
var history []string

Next, whenever we get new input, we are going to store it in the history

// Add the new input to the history
history = append(history, input)

Finally, chatbot is going to check for a ‘prompt’ that it will use to print the history.

// Check if the input was the string 'history'
if input == "history" {
	// iterate (loop) through the history
	for k, v := range history {
		// print out the Key and the Value
		fmt.Println(k, v)
	}
}

Step 4: Putting it all together

The completed above code can be found in this github repository. There is a main.go file (the code) and a README.md file (the directions).

To get the following output, run the program, and enter the following lines

1. type test
2. type cool
3. type history

Well, we’ve now got a chatbot that is still a copycat. It can now recount all the things it has copied. This ‘history’ only lasts while the program is running. In future lessons, we can explore more permanent memory, command logic, and making the code organized.