Revisiting-Concepts-Notations-Software-Art/2.Ghost-Writing.md

# Ghost Writing: Text, Arrays, Randomness

<p align="center">
<img src="https://git.le-club-des-sans-sujets.org/gauthiier/Revisiting-Concepts-Notations-Software-Art/media/branch/main/img/love-letter.png" width="80%"/>	
</p>

## Sketch: 2.0 Array + Index

```javascript
// Array + Index!

var NAMES = ["David", "Karin", "Sigrid", "Nanna", "Laura", "Maaike"];
var INDEX = 0;
    
function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(220);
}

function keyTyped() {
  if(key == 'x') {
    print("Hi " + NAMES[0] + "!");
  }
}

// Reference: https://p5js.org/reference/
```

### 🤔 What are indices?

```javascript
 ["David", "Karin", "Sigrid", "Nanna", "Laura", "Maaikke"]  <--- Array (var NAMES)
     |        |         |        |         |        |
     0        1         2        3         4        5		<--- indices (var INDEX)
```

### 📚 Exercise

1. Modify sketch 2.0 so that:
* When key ```'k'``` is typed then ```"Hi Karin!"``` is printed on the console
* When key ```'s'``` is typed then ```"Hi Sigrid!"``` is printed on the console
* When key ```'n'``` is typed then ```"Hi Nanna!"``` is printed on the console
* When key ```'m'``` is typed then ```"Hi Maaike!"``` is printed on the console

2. Modify sketch 2.0 so that:
* Every time key ```'x'``` is typed then print the name of the following person in the array (```"Hi David!"```, ```"Hi Karin!"```, ```"Hi Sigrid!"```, and so forth)

### 🤔 Who/what is "undefined"?

<p align="center">
<img src="https://git.le-club-des-sans-sujets.org/gauthiier/Revisiting-Concepts-Notations-Software-Art/media/branch/main/img/undefined.png">	
</p>

## Sketch: 2.1 Array + Index + Loop

```javascript
// Array + Index + Loop!

var NAMES = ["David", "Karin", "Sigrid", "Nanna", "Laura", "Maaike"];
var ACTIVITIES = ["piano", "tennis", "chess", "records"];
var INDEX = 0;
    
function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(220);
}

function keyTyped() {
  if(key == 'x') {
    for(let i = 0; i < ACTIVITIES.length; i++) {
      print(NAMES[INDEX] + " likes to play " + ACTIVITIES[i]);  
    }
  }
}

// Reference: https://p5js.org/reference/
```

### 🤔 How do for-loops work?

```javascript
for(let i = 0; i < X; i++) {
  // do_somethings();
}
```
where

```javascript
let i = 0 
// is the declaration and initialisation of the control variable (i)

i < X 
//is the loop continuation condition: if the condition is true, the statement in the loop [do_something();] is executed, otherwise exit the loop when the condition is false

i++
//is the incremental (update) statement that is executed at the end of the loop (i.e. just after the loop statement [do_something();] as been executed) 
```

### 📚 Exercise

1. Modify skecth 2.1 so that every one listed in the ```NAMES``` array have all the activities listed in the ```ACTIVITIES``` array be printed out on the console when key ```'x'``` is typed (this is called a nested loop!). The console output should look something like:

```
Karin likes to play piano 
Karin likes to play tennis 
Karin likes to play chess 
Karin likes to play records 
Sigrid likes to play piano 
Sigrid likes to play tennis 
Sigrid likes to play chess 
Sigrid likes to play records 
Nanna likes to play piano 
Nanna likes to play tennis 
Nanna likes to play chess 
(etc.)
```

## Sketch: 2.2 Array + Index + Randomness

Randomness in p5js is based on generating a random number between 0 and a specified maximum. 

Typically a random number is produced with the ```random``` function: 
```javascript
random(X); // generates a random number between 0 and X
````
Here is an example:
```javascript
let random_number = random(10); // assign a random number between 0 and 10 to variable random_number
````

Rudimentary indeed, but there are many things we can build with this simple function!

### 🤔 How to select a random element in an array?

Since we access elements of an array with indices, we can generate a random index between 0 and the length of an array so to select a random element in it.

The first problem we have to solve is that the ```random``` functions generates a "real" number (ex: 4.993319470244624, 1.9486631456631776, 7.1841821754535813, etc.) while the indices of an array are "integer" numbers (5, 2, 7, etc.). 

We thus need to round the "real" numbers produced by random (4.993319470244624 -> 5, 1.9486631456631776 -> 2, 7.1841821754535813 -> 7). We do this with the ```floor``` function:

```javascript
let random_number = floor(random(10)); // assign a random integer number between 0 and 10 to variable random_number
````

With this "fix" we can generate a random index (integer) between 0 and the length of a given array.

```javascript
var NAMES = ["David", "Karin", "Sigrid", "Nanna", "Laura", "Maaike"];

let random_index_names = floor(random(NAMES.length));

print(NAMES[random_index_names]);
````

This will indeed print a random name in the array ```NAMES``` each time it is executed. 

But what if we would like to print a random activity from the ```ACTIVITIES``` array as well? 

```javascript
var NAMES = ["David", "Karin", "Sigrid", "Nanna", "Laura", "Maaike"];
var ACTIVITIES = ["piano", "tennis", "chess", "records"];

let random_index_names = floor(random(NAMES.length));
let random_index_activities = floor(random(ACTIVITIES.length));

print(NAMES[random_index_names] + " likes to play " +  ACTIVITIES[random_index_activities]);
````

This will work, but it is not "elegant"... We have here two variables (```random_index_names```, ```random_index_activities```) that are assigned a random value with the respective arrays' length (```NAMES.length```, ```ACTIVITIES.length```). What if we had many arrays? We would need as many variables as there are arrays to select from right? The code would be very long!

To remediate this tedious need to write too much code, how about writing a function that selects a random element from an "generic" array? 

Here is an example of a custom "choice" function taking an array as input and returns a randomly selected elements from the array:

```javascript
// function selecting a random element from an array
function choice(array_to_choose_from) {
	let random_index = floor(random(array_to_choose_from.length));
	return array_to_choose_from[random_index];
}
````



```javascript
// Array + Index + Randomness!

var NAMES = ["David", "Karin", "Sigrid", "Nanna", "Laura", "Maaike"];
var ACTIVITIES = ["piano", "tennis", "chess", "records"];
    
function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(220);
}

// function selecting a random element from an array
function choice(array_to_choose_from) {
	let random_index = floor(random(array_to_choose_from.length));
	return array_to_choose_from[random_index];
}

function keyTyped() {
  if(key == 'x') {
    print(choice(NAMES) + " likes to play " + choice(ACTIVITIES) + " with " + choice(NAMES));
  }
}

// Reference: https://p5js.org/reference/
````

### 📚 Exercise

1. Modify sketch 2.2 by adding a day of the week when an activity is taking place. For example: 

```
David likes to play records with Karin on Tuesday
```

2. Come up with your own random sentences! Remember you can add as many arrays to select from as you want and most languages are structured "systems" having nouns, verb, adjectives, adverbs, etc. Here is what I came up with (can you guess what my code looks like?):

```
Laura wears a blue sweater when Sigrid plays tennis 
Karin wears a black cap when Karin plays records 
Laura wears a expensive scarf when Karin plays records  
Karin wears a yellow jacket when Sigrid plays chess 
David wears a ridiculous scarf when Sigrid plays records
Karin wears a black jacket when Maaike plays chess 
```

## ✍️ Christopher Strachey's Love Letters

<p align="center">
<img src="https://git.le-club-des-sans-sujets.org/gauthiier/Revisiting-Concepts-Notations-Software-Art/media/branch/main/img/Strachey-Mark1.png" width="100%"/>	
</p>

So now that we have a better understanding of how arrays, indices, randomness, and functions work, let's write love letters!

One of the first non-scientific computer program that was ever written is Christopher Strachey's Love Letters program for the Manchester Mark I (so called [Baby](https://content.presspage.com/uploads/1369/1920_themanchestermk1computerbuiltbyextendingthebaby.jpg?10000)). In fact, this computer program (written in 1952 and making use of randomness) is arguably the first art-inspired program! Christopher Strachey was a computer programming pioneer who worked along Alan Turing in the very early days of computing at the University of Manchester. Strachey's story is fascinating. There is a great article about [him and the love letters on Rhizome's Queer History of Computing written by Jacob Gaboury](https://rhizome.org/editorial/2013/apr/9/queer-history-computing-part-three/). For those who are interested in researching Strachey's work, please have a look at his [papers and correspondences at the Bodleain library's archive](https://archives.bodleian.ox.ac.uk/repositories/2/resources/2561).

Strachey's Love Letters have been studied before. [David Link](http://www.alpha60.de) did a colossal reconstitution of the Love Letter program on a simulator of the Manchester Mark computer. [The works was exhibited circa 2010](http://www.alpha60.de/art/love_letters/). The program doesn't look at all like the code we are writing at the moment! The picture on the right side above (☝️) is from Link's simulator. Early computers did not have the compilers and interpreters we have now (remember compilers and interpreters) and thus the code was written in a rather cryptic way (believe me, way more cryptic than what we are writing). 

The program we are about to write in a "modern" computing language (i.e. javascript/p5js) is a modified version of [Nick Montfort](https://nickm.com)'s letter.py source code written in python. Montfort's letter.py was based on Noah Wardrip-Fruin's article ["Digital Media Archaeology."](https://www.degruyter.com/document/doi/10.1525/9780520948518-016/html)


### Analysing Love Letters' structure

First, let's have a look at love letters to see what they look like. David Link has generated an [archive of simulated letters](http://www.alpha60.de/art/love_letters/archive/muc/). 

Here are four examples: 

``` 
HONEY MOPPET
        YOU ARE MY AMOROUS RAPTURE.: MY KEEN LOVE. MY COVETOUS
 INFATUATION THIRSTS FOR YOUR FERVENT LIKING. YOU ARE MY
 CRAVING LIKING. MY CURIOUS RAPTURE FONDLY THIRSTS FOR YOUR
 ANXIOUS ENCHANTMENT.
                             YOURS COVETOUSLY
MUC
```

```
DEAR DARLING
        MY ADORABLE FELLOW FEELING WANTS YOUR SWEET INFATUATION
. MY ADORABLE ARDOUR LOVINGLY WISHES YOUR FERVOUR. MY
 UNSATISFIED FELLOW FEELING EAGERLY HUNGERS FOR YOUR IMPATIENT
 DESIRE. YOU ARE MY LOVING FERVOUR. MY WINNING WISH YEARNS FOR YOUR
 KEEN HEART.
                             YOURS FERVENTLY
MUC
```

```
HONEY HONEY
        MY BURNING FANCY EAGERLY TEMPTS YOUR INFATUATION.
 YOU ARE MY FERVENT YEARNING. MY LIKING BEAUTIFULLY YEARNS FOR YOUR
 LOVE. MY APPETITE TENDERLY CHERISHES YOUR BEAUTIFUL WISH.
 YOU ARE MY EROTIC ADORATION.
                             YOURS SEDUCTIVELY
MUC
```

```
DARLING LOVE
        YOU ARE MY AMOROUS ENCHANTMENT.: MY KEEN EAGERNESS.
 YOU ARE MY DEVOTED ENCHANTMENT. MY YEARNING FERVENTLY LIKES
 YOUR AMOROUS PASSION. MY EAGERNESS TENDERLY YEARNS FOR YOUR
 PASSION.
                             YOURS ARDENTLY
MUC
```

```
HONEY LOVE
        MY AVID CHARM EAGERLY LOVES YOUR LOVING ENTHUSIASM. MY
 AMBITION LUSTS AFTER YOUR LOVE. MY HUNGER THIRSTS FOR YOUR
 ENTHUSIASM. MY ADORABLE LONGING AFFECTIONATELY PINES FOR YOUR
 DEVOTION. MY FONDNESS PASSIONATELYFTER YOUR IMPATIENT
 FERVOUR.
                             YOURS KEENLY
MUC
```

Can you decipher certain writing patterns in the above formulations? If so, what are they?

Consider the following sentences:

```
MY YEARNING FERVENTLY LIKES YOUR AMOROUS PASSION.
MY APPETITE TENDERLY CHERISHES YOUR BEAUTIFUL WISH.
```

We can "code" this sentence as follow:

MY + ```noun``` + ```adverb``` + ```verb``` + YOUR + ```adjective``` + ```noun``` + .

In fact, we could even add an ```adjective``` before the first ```noun``` as to make it even more "wordy":

MY + ```adjective``` + ```noun``` + ```adverb``` + ```verb``` + YOUR + ```adjective``` + ```noun``` + .

Now consider this sentence, whose structure seems to come up often:

```
YOU ARE MY AMOROUS RAPTURE.
```

Let's "code" this like:

YOU ARE MY + ```adjective``` + ```noun``` + .

There is also this small phrase:

```
MY KEEN EAGERNESS.
```

Which can be coded as:

MY + ```adjective``` + ```noun``` + .

So we have two types of sentences: 
* long form: MY + ```noun``` + ```adverb``` + ```verb``` + YOUR + ```adjective``` + ```noun``` + . 
* short form: YOU ARE MY + ```adjective``` + ```noun``` + . OR MY + ```adjective``` + ```noun``` + .

In terms of sentences sequencing we notice that: 
1. A letter always starts with a certain opening {HONEY or DEAR or DARLING} + {MOPPET or DARLING or HONEY or LOVE}
2. the short form MY + ```adjective``` + ```noun``` + . always follows the other short form YOU ARE MY + ```adjective``` + ```noun``` + . This short form never follows the long form.
3. short form YOU ARE MY + ```adjective``` + ```noun``` + . is never followed by the same short form YOU ARE MY + ```adjective``` + ```noun``` + .
4. There are between 4 and 5 sentences (long or short form) per letter
5. A letter is always complementary closed with YOURS + ```adverb```
6. A letter is always signed by MUC (which means Manchester University Computer Department)


### Reconstituting Love Letters' algorithm

Now that we have an idea of the structure of Strachey's letters, let's get to work in formalising it's algorithmic generation. 

Luckily, in terms of vocabulary, we can start with Monfort's arrays:

```javascript
// vocabulary
const first = ['DARLING', 'DEAR', 'HONEY', 'JEWEL'];
const second = ['DUCK', 'LOVE', 'MOPPET', 'SWEETHEART'];
const adjectives = ['ADORABLE', 'AFFECTIONATE', 'AMOROUS', 'ANXIOUS', 'ARDENT', 'AVID', 'BREATHLESS', 'BURNING', 'COVETOUS', 'CRAVING', 'CURIOUS', 'DARLING', 'DEAR', 'DEVOTED', 'EAGER', 'EROTIC', 'FERVENT', 'FOND', 'IMPATIENT', 'KEEN', 'LITTLE', 'LOVEABLE', 'LOVESICK', 'LOVING', 'PASSIONATE', 'PRECIOUS', 'SWEET', 'SYMPATHETIC', 'TENDER', 'UNSATISFIED', 'WISTFUL'];
const nouns = ['ADORATION', 'AFFECTION', 'AMBITION', 'APPETITE', 'ARDOUR', 'CHARM', 'DESIRE', 'DEVOTION', 'EAGERNESS', 'ENCHANTMENT', 'ENTHUSIASM', 'FANCY', 'FELLOW FEELING', 'FERVOUR', 'FONDNESS', 'HEART', 'HUNGER', 'INFATUATION', 'LIKING', 'LONGING', 'LOVE', 'LUST', 'PASSION', 'RAPTURE', 'SYMPATHY', 'TENDERNESS', 'THIRST', 'WISH', 'YEARNING'];
const adverbs = ['AFFECTIONATELY', 'ANXIOUSLY', 'ARDENTLY', 'AVIDLY', 'BEAUTIFULLY', 'BREATHLESSLY', 'BURNINGLY', 'COVETOUSLY', 'CURIOUSLY', 'DEVOTEDLY', 'EAGERLY', 'FERVENTLY', 'FONDLY', 'IMPATIENTLY', 'KEENLY', 'LOVINGLY', 'PASSIONATELY', 'SEDUCTIVELY', 'TENDERLY', 'WINNINGLY', 'WISTFULLY'];
const verbs = ['KICKS', 'ADORES', 'ATTRACTS', 'CARES FOR', 'CHERISHES', 'CLINGS TO', 'DESIRES','HOLDS DEAR', 'HOPES FOR', 'HUNGERS FOR', 'IS WEDDED TO', 'LIKES', 'LONGS FOR', 'LOVES', 'LUSTS AFTER', 'PANTS FOR', 'PINES FOR', 'PRIZES', 'SIGHS FOR', 'TEMPTS', 'THIRSTS FOR', 'TREASURES', 'WANTS', 'WISHES', 'WOOS', 'YEARNS FOR'];

```

Which we can randomly select from with our ```choice``` function we devised earlier:

```javascript
// function selecting a random element from an array
function choice(array_to_choose_from) {
	let random_index = floor(random(array_to_choose_from.length));
	return array_to_choose_from[random_index];
}
```

With both these elements we can start devising the code of the long form we identified above. 

MY + ```noun``` + ```adverb``` + ```verb``` + YOUR + ```adjective``` + ```noun``` + . 

Let's do this coding with a function again:

```javascript
// function that randomly generates a long form sentence
function long() {
	return "MY " + choice(nouns) + " " + choice(adverbs) + " " + choice(verbs) + " YOUR " + choice(adjectives) + " " + choice(nouns) + ".";
}
````

This will certainly work. Yet I would like to have more variation with the sentences the function returns. At the moment it will always follow the long form structure.

How about we make ```adjective``` and ```adverb``` non mandatory, meaning they maybe there or maybe not. What I have in mind is something like:

```javascript
// function that randomly generates a long form sentence
function long() {
	return "MY " + maybe(adjectives) + " " + choice(nouns) + " " + maybe(adverbs) + " " + choice(verbs) + " YOUR " + maybe(adjectives) + " " + choice(nouns) + ".";
}
````

To decide if an element (```adjective``` or ```adverb```) should be part of the sentence or not we need to write a ```maybe``` function which randomly chooses true or false if the element should be chosen from a given array.

```javascript
// function that randomly decides if an element from an array should be selected or not
function maybe(array_to_choose_from) {
	// choose between true or false
	if(choice([true, false])) {
		// if true then return an element from the array
		return choice(array_to_choose_from);
	} else {
		// otherwise return and empty sentence (i.e. nothing)
		return "";
	}
}
````
With this ```maybe``` function we now have a way to diversify the letter's sentences and thus create more variation on our generated long forms.

How about the short forms then?  

YOU ARE MY + ```adjective``` + ```noun``` + .
MY + ```adjective``` + ```noun``` + .

We can simply write a ```short``` function like:

```javascript
// function that randomly generates a short form sentence
function short() {
	return choice(adjectives) + ' ' + choice(nouns) + '. ';
}
```

And prefix it with YOU ARE MY or MY when we are in the midst of writing the sequence of sentences. This might become clearer below.

How about the opening? Notice the ```first``` and ```second``` in the vocabulary. These are exactly what we need:

```javascript
// function that randomly an opening
function opening() {
	return choice(first) + ' ' + choice(second);
}
```

And the closing in form YOURS + ```adverb```? Simple:

```javascript
// function that randomly a closing
function closing() {
	return "YOURS " + choice(adverbs);
}
```

Now we have most of the ingredients in place with the functions ```choice```, ```maybe```, ```long```, ```short```, ```opening```, ```closing``` right?

How about sequencing ```long``` and ```short``` forms? Remember what we observed above (i.e. a letter is 4 to 5 sentences long, short form MY + ```adjective``` + ```noun``` + . always follows the other short form, etc.)? 

Following these observation here is a skeleton of an algorithm doing just that:

```javascript
// start with an empty text
var text = "";

// did we just wrote the short form with "YOU ARE MY"
let YOU_ARE = false;

// loop 5 times to generate 5 sentences
for(let i = 0; i < 5; i++) {

	// choose if the next sentence is a short or long
	let sentence_form = choice(['short', 'long']);

	if(sentence_form == 'short') {
		// there's two types of short to switch from

		// the short form MY + ```adjective``` + ```noun``` + .
		// always follows the YOU ARE MY + ```adjective``` + ```noun``` + . one
		// and
		// the short form YOU ARE MY + ```adjective``` + ```noun``` + . one
		// can never follow itself

		// this means we need keep track of when "YOU ARE MY" is generated
		// and switch to the other form next time. This is what the variable 
		// YOU_ARE is doing 

		if(YOU_ARE) {
			// the ": MY" can only follow a "YOU ARE MY"
			text += ": MY " + short();
			YOU_ARE = false;
		} else {
			text += "YOUR ARE MY " + short();
			// the ": MY" can only follow a "YOU ARE MY"
			YOU_ARE = true;
		}
	} else if(sentence_form == 'long') {
		text += long();
		// make sure the next sentence is not ": MY"
		YOU_ARE = false
	}
}
````



### Putting it all together 

Ok, let's formalise what we have sketched above and write a ```write_letter``` function that returns and actually full fleshed love letter. 

```javascript
// function returning a love letter
function write_letter(){
	var text = "";

	// write the letter's opening 
	text += opening();
	text += "\n";			// this is a new line!

	// did we just wrote the short form with "YOU ARE MY"
	let YOU_ARE = false;

	// write 5 sentences
	for(let i = 0; i < 5; i++) {

		// choose if the next sentence is a short or long
		let sentence_form = choice(['short', 'long']);

		if(sentence_form == 'short') {
			// there's two types of short to switch from
			if(YOU_ARE) {
				// the ": MY" can only follow a "YOU ARE MY"
				text += ": MY " + short();
				YOU_ARE = false;
			} else {
				text += "YOUR ARE MY " + short();
				// the ": MY" can only follow a "YOU ARE MY"
				YOU_ARE = true;
			}
		} else if(sentence_form == 'long') {
			text += long();
			// make sure the next sentence is not ": MY"
			YOU_ARE = false;
		}
	}

	text += "\n";			// this is a new line!

	// write the letter's closing
	text += "						" + closing();

	text += "\n";			// this is a new line!

	// sign
	text += "MUC";

	// return the letter's text
	return text;
}
```

This function follows the algorithm we wrote above and adds the opening and closing sequence. 

If you followed me during the session you should have a sketch looking more or less like the following, comprising all the functions we wrote. Here the letter is printed when ```x```is typed.

```javascript
// Strachey's Love Letter generator!

// vocabulary
const first = ['DARLING', 'DEAR', 'HONEY', 'JEWEL'];
const second = ['DUCK', 'LOVE', 'MOPPET', 'SWEETHEART'];
const adjectives = ['ADORABLE', 'AFFECTIONATE', 'AMOROUS', 'ANXIOUS', 'ARDENT', 'AVID', 'BREATHLESS', 'BURNING', 'COVETOUS', 'CRAVING', 'CURIOUS', 'DARLING', 'DEAR', 'DEVOTED', 'EAGER', 'EROTIC', 'FERVENT', 'FOND', 'IMPATIENT', 'KEEN', 'LITTLE', 'LOVEABLE', 'LOVESICK', 'LOVING', 'PASSIONATE', 'PRECIOUS', 'SWEET', 'SYMPATHETIC', 'TENDER', 'UNSATISFIED', 'WISTFUL'];
const nouns = ['ADORATION', 'AFFECTION', 'AMBITION', 'APPETITE', 'ARDOUR', 'CHARM', 'DESIRE', 'DEVOTION', 'EAGERNESS', 'ENCHANTMENT', 'ENTHUSIASM', 'FANCY', 'FELLOW FEELING', 'FERVOUR', 'FONDNESS', 'HEART', 'HUNGER', 'INFATUATION', 'LIKING', 'LONGING', 'LOVE', 'LUST', 'PASSION', 'RAPTURE', 'SYMPATHY', 'TENDERNESS', 'THIRST', 'WISH', 'YEARNING'];
const adverbs = ['AFFECTIONATELY', 'ANXIOUSLY', 'ARDENTLY', 'AVIDLY', 'BEAUTIFULLY', 'BREATHLESSLY', 'BURNINGLY', 'COVETOUSLY', 'CURIOUSLY', 'DEVOTEDLY', 'EAGERLY', 'FERVENTLY', 'FONDLY', 'IMPATIENTLY', 'KEENLY', 'LOVINGLY', 'PASSIONATELY', 'SEDUCTIVELY', 'TENDERLY', 'WINNINGLY', 'WISTFULLY'];
const verbs = ['KICKS', 'ADORES', 'ATTRACTS', 'CARES FOR', 'CHERISHES', 'CLINGS TO', 'DESIRES','HOLDS DEAR', 'HOPES FOR', 'HUNGERS FOR', 'IS WEDDED TO', 'LIKES', 'LONGS FOR', 'LOVES', 'LUSTS AFTER', 'PANTS FOR', 'PINES FOR', 'PRIZES', 'SIGHS FOR', 'TEMPTS', 'THIRSTS FOR', 'TREASURES', 'WANTS', 'WISHES', 'WOOS', 'YEARNS FOR'];

    
function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(220);
}

// function selecting a random element from an array
function choice(array_to_choose_from) {
	let random_index = floor(random(array_to_choose_from.length));
	return array_to_choose_from[random_index];
}

// function that randomly decides if an element from an array should be selected or not
function maybe(array_to_choose_from) {
	// choose between true or false
	if(choice([true, false])) {
		// if true then return an element from the array
		return choice(array_to_choose_from);
	} else {
		// otherwise return and empty sentence (i.e. nothing)
		return "";
	}
}

// function that randomly generates a long form sentence
function long() {
	return "MY " + maybe(adjectives) + " " + choice(nouns) + " " + maybe(adverbs) + " " + choice(verbs) + " YOUR " + maybe(adjectives) + " " + choice(nouns) + ".";
}

// function that randomly generates a short form sentence
function short() {
	return choice(adjectives) + ' ' + choice(nouns) + '. ';
}

// function that randomly an opening
function opening() {
	return choice(first) + ' ' + choice(second);
}

// function that randomly a closing
function closing() {
	return "YOURS " + choice(adverbs);
}

// function returning a love letter
function write_letter(){
	var text = "";

	// write opening 
	text += opening();
	text += "\n";			// this is a new line!

	let YOU_ARE = false;
	// write 5 sentences
	for(let i = 0; i < 5; i++) {

		// choose if the next sentence is a short or long
		let sentence_form = choice(['short', 'long']);

		if(sentence_form == 'short') {
			// there's two types of short to switch from
			if(YOU_ARE) {
				// the ": MY" can only follow a "YOU ARE MY"
				text += ": MY " + short();
				YOU_ARE = false;
			} else {
				text += "YOUR ARE MY " + short();
				// the ": MY" can only follow a "YOU ARE MY"
				YOU_ARE = true;
			}
		} else if(sentence_form == 'long') {
			text += long();
			// make sure the next sentence is not ": MY"
			YOU_ARE = false;
		}
	}

	text += "\n";			// this is a new line!

	// write closing
	text += "						" + closing();

	text += "\n";			// this is a new line!

	// sign
	text += "MUC";

	// return the letter
	return text;
}

function keyTyped() {
  if(key == 'x') {
    let letter = write_letter();
    print(letter);
  }
}

// Reference: https://p5js.org/reference/
```

The output of our program print something like this:

<p align="center">
<img src="https://git.le-club-des-sans-sujets.org/gauthiier/Revisiting-Concepts-Notations-Software-Art/src/commit/317e343a3609e4a4e21246955fdea386b3017cb8/img/letter-output.png" width="100%"/>	
</p>


There might be minor formatting issues with the code above. I'll let you fix them as you inspect what the code does when it prints to the console.