Pseudocode Poems

A purple flower with dew drops — Image by AdelinaZw from Pixabay

Pseudocode poems are poems that work both as a poem and as an algorithm so can be read or executed. They incorporate sequencing, selection or repetition constructs and other kinds of statements to take actions. You can implement them as an actual program. Below are our attempts. Can you write better ones?

Poems often use the ambiguity in language and aim to affect emotions. Pseudocode is intended to be precise. Programs certainly are. They do something specific and have a single precise meaning. Writing pseudocode poems that do both can be a lot of fun: just like writing normal programs is. The idea was inspired by Bryan Bilston’s poem ‘Two Paths Diverged’. Read it here or buy his wonderful book of poems, ‘ You took the last bus home’.

I am not a great poet, but here are some of my attempts at pseudocode poems to at least give you the idea. They are, in turn, based on the core control structures of Sequencing, Selection and Repetition. They also use print statements and assignments to get things done,

Sequencing

This pseudocode poem is based on sequencing: doing things one after the other.

What am I when it’s all over?

I am dire.
I am fire.

I am alone.
I am stone.

I am old.
I am cold.

We use the verb TO BE to be the equivalent of assignment: setting the value of a variable. Here it is implemented as a Python program.

def whatamI():
	"""What am I when it's all over?"""

	I = 'dire'
	I = 'fire'
	
	I = 'alone'
	I = 'stone'
	
	I = 'old'
	I = 'cold'
	
	print(I)

Selection

Here is a pseudocode poem based on selection, which is the second core control structure. It chooses between two option based on a boolean test: a true / false question. The question here is: do I love you? Dry run the algorithm or run program to find out.

Violets are violet
if roses are red and violets are blue
then
    Life is sweet
else
    I love you

Here it is implemented as a Python program (with appropriate initialisation).

def violetsareviolet():
	"""Violets are violet"""
	roses = 'red'
	violets = 'violet'
	
	if roses == 'red' and violets == 'blue':
		print('Life is sweet')
	else:
		print('I love you')

violetsareviolet()

Find out more about Selection based pseudocode programs via our computational literary criticism of Rudyard Kipling’s poem “If”.

Iteration or Repetition

The final kind of control structure is iteration (i.e., repetition). It is used to repeat the same lines over and over again.

Is this poem really long?

it is true
while it is true
    this is short
it is endless

Here it is implemented as a Python program.

def isthispoemreallylong():
    """Is this poem really long?"""
    it = True
    while (it == True) :
        this = 'short'
    it = 'endless'

isthispoemreallylong()

Can you work out what it does as an algorithm/program, rather than as just a normal poem? You may need a version with print statements to understand its beauty.

def isthispoemreallylong2():
    """Is this poem really long?"""
    it = True
    while (it == True) :
        this = 'short'
        print("this is " + this)
    it = 'endless'
    print("it is " + it)

isthispoemreallylong2()

The word while indicates the start of a while loop. In the pseudocode, it is a command to repeat the following statement(s). It checks the boolean expression after the body each time. Only if that boolean expression is false does it stop. In this case the body sets the variable named this to string value ‘short’. The test is about a different variable though which is not changed inside the loop, so once in the loop there is nothing that will ever change the variable it so the value of the test will always be the same. Variable it will always be True and the loop will keep setting variable this to value ‘short’, over and over again. This means the loop is a non-terminating loop. It never exits so the lines of code after it are never executed. As a program they are never followed by the computer. The variable it is never set to the value ‘endless’.

Overall the poem is short in number of lines but it is actually endless if executed. It is the equivalent of a poem that once you start reading it you never get to the end:

it is true 
check it is true 
this is short
check it is true 
this is short
check it is true 
this is short
...

Here is a more romantically inclined poem for Valentine’s day (since at the time of writing, it is coming up) again using repetition

My love for you is endless

my love is true
while my love is true
    I love you

Here it is implemented as a Python program.

def myloveforyouisendless():
"""My love for you is endless"""
my_love = True
while my_love == True:
    print('I love you')

myloveforyouisendless()

Pseudovode love poem surrounded by hearts

In the pseudocode of this poem the verb “to be” is used for two different purposes: as an assignment statement (it is true is used as a statement to mean it = True) and as a boolean expression (it is true is used as a boolean expression to mean it == True). As an assignment it is used as a command to do something. As an expression it is something representing a value: it evaluates to either true or false. Confusing these two English uses is a common mistake novices make programming, and shows one of the ways why programming languages are used with different symbols for different meanings, rather than natural languages.

Now it is your turn. Can you write a great poem that can also be executed?

Paul Curzon, Queen Mary University of London

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This blog is funded by EPSRC on research agreement EP/W033615/1.

Answers

The selection poem is about a volcano, but the answer to the question in the title is ‘cold’.
Assuming you agree with me that violet flowers are violet (or at least not blue) then clearly we are compatible at least in being pedantic and you will find I love you.

If: a computational literary criticism

If, by Rudyard Kipling is an inspirational poem that was voted the UKs favourite poem in the 1990s. It consists of a series of lines that start with If. What If, by Benjamin Zephaniah is a more subversive poem modelled on the original.

If statements, of course, are a really core part of programs so are these poems, given they are all about IF, algorithms? The use of If here isn’t quite the same as a pure computational one as seen in programs. For a start, it doesn’t follow the structure of a computer science IF statement. Here are a few lines:

If you can keep your head when all about you
  Are losing theirs and blaming it on you,
If you can trust yourself when all men doubt you,
  But make allowance for their doubting too;
...

In programs, an IF statement has a specific structure. It consists of a test of something that is true or false but then gives a specific action to take when the statement is true. The lines

you can keep your head when all about you are losing theirs AND blaming it on you,

is more or less such a true or false statement. Either you can keep your head or you can’t. This though ignores the possibility of you sometimes losing your head and sometimes not. The poem presumably means to say that you must ALWAYS keep your head. What exactly does “when” here mean too? The reason we do not use English when writing programs is the lack of clarity of what is actually meant. Programs are mathematically precise in their meaning. They do only have one possible meaning (and that is the point). this is also a potential issue of writing programs by instructing AIs over what you want in English!

This boolean expression (something that evaluates to true or false) also uses a logical connective AND just like in a program – you must both be keeping your head AND people must be blaming it on you for the whole to be true. If they are both true then the action that follows is taken, but if they aren’t both true the poem says nothing about you!

Another issue in If, is that this test / boolean expression is not immediately followed by an action to do when it is true. The action comes right at the very end of the poem

...
Yours is the Earth and everything that's in it,
And - which is more - you'll be a Man, my son!

This comes after a whole series of these partial IF statements. To make it more clearly like a program you would add a more explicitly IF-THEN structure, which is the equivalent of putting ANDs between all the tests. In a program that would be written more like the following:

IF you can keep your head when all about you
  Are losing theirs and blaming it on you,
   THEN IF you can trust yourself when all men doubt you,
              But make allowance for their doubting too;
...
...
                             THEN Yours is the Earth and everything that's in it,
                                        And - which is more - you'll be a Man, my son!

Only if all the tests are true does the final action get taken. Though it isn’t really an action, it is more an assertion that something else is true – “the Earth is yours”, rather than “we give you the Earth”. (Also that final And is no longer a logical connective!)

Poems like this could be made more explicitly computational though. For example, a slightly more computational version might be:

IF you can keep your head when all about you
   Are losing theirs AND blaming it on you
THEN I will thank you, giving you a pay rise too
...

A love poem in this vein might start

IF you are a snail 
    THEN I will become your shell.
IF you are a ...

This leads on to the idea of pseudocode poems, that use other computational constructs. More of that to come.

To do …

Write your own poem in this style with true/false questions followed by specific actions, modelled on the computational version of IF. It could be a reworking of If itself or a completely different poem.

Transitional Automaton: a poem

My poetry collection, «Αλγόριθμοι Σιωπής» (Algorithms of Silence), explores the quiet, often unseen structures that shape our inner lives. As a computer scientist and a poet, I’m fascinated by the language we use to describe these systems – whether they are emotional, social, or computational.

The following piece is an experiment that embodies this theme. It presents a single core idea – about choice, memory, and predetermination – in three different languages: the original Greek poem “Αυτόματον Μεταβατικόν,” an English transcreation, and a pseudocode version that translates the poem’s philosophical questions into the logic of an automaton.

– Vasileios Klimis, Queen Mary University of London

Transitional Automaton

Once,
a decision – small,
like a flaw in a cogwheel –
tilted the whole system toward a version
never written.

In the workshop of habits,
every choice left behind
a trace of activation;
you don’t see it,
but it returns
like a pulse
through a one-way gate.

•

I walk through a matrix of transitions
where each state defines the memory of the next.
Not infinite possibilities –
only those the structure permits.

Is this freedom?
Or merely the optimal illusion
of a system with elastic rules?

•

In moments of quiet
(but not of silence)
I feel the null persisting
not as absence,
but as a repository in waiting.
Perhaps that is where it resides,
all that was never activated.

•

If there is a continuation,
it will resemble a debug session
more than a crisis.

Not a moral crisis;
a recursion.
Who passes down to the final terminal
the most probable path?

•

The question is not
what we lived.
But which of the contingencies
remained active
when we
stopped calculating.

Αυτόματον μεταβατικόν

Κάποτε,
μια απόφαση – μικρή, σαν στρέβλωση σε οδοντωτό τροχό –
έγερνε το σύνολο προς μια εκδοχή
που δεν γράφτηκε ποτέ.

•

Στο εργαστήριο των συνηθειών
κάθε επιλογή άφηνε πίσω της
ένα ίχνος ενεργοποίησης·
δεν το βλέπεις,
αλλά επιστρέφει
σαν παλμός σε μη αντιστρεπτή πύλη.

•

Περπατώ μέσα σ’ έναν πίνακα μεταβάσεων
όπου κάθε κατάσταση ορίζει τη μνήμη της επόμενης.
Όχι άπειρες πιθανότητες –
μόνον όσες η δομή επιτρέπει.
Είναι ελευθερία αυτό;
Ή απλώς η βέλτιστη πλάνη
ενός συστήματος με ελαστικούς κανόνες;

•

Σε στιγμές σιγής (αλλά όχι σιωπής)
νιώθω το μηδέν να επιμένει
όχι ως απουσία,
αλλά ως αποθήκη αναμονής.
Ίσως εκεί διαμένει
ό,τι δεν ενεργοποιήθηκε.

•

Αν υπάρξει συνέχεια,
θα μοιάζει περισσότερο με debug session
παρά με κρίση.

•

Όχι κρίση ηθική·
μία αναδρομή.
Ποιος μεταβιβάζει στο τερματικό του τέλους
το πιο πιθανό μονοπάτι;

•

Η ερώτηση δεν είναι τι ζήσαμε.
Αλλά ποιο από τα ενδεχόμενα έμεινε ενεργό
όταν εμείς
σταματήσαμε να υπολογίζουμε.

Pseudocode Poem version

Pseudocode poems are poems written in pseudocode: the semi-formailsed language used for writing algorithms and planning the design of program. Here is the above poem as a pseudocode poem.

FUNCTION life_automaton(initial_state)
  DEFINE State_Transitions AS Matrix;
  DEFINE active_path AS Log;
  DEFINE potential_paths AS Set = {all_versions_never_written};

  current_state = initial_state;
  system.log("Initializing in the workshop of habits.");

  REPEAT

    WAIT FOR event.decision;
    // a decision — small, like a flaw in a cogwheel
    IF (event.decision.is_subtle) THEN
       previous_state = current_state;
       current_state = State_Transitions.calculate_next
                                (previous_state, event.decision);
       // it returns like a pulse through a one-way gate
       active_path.append(previous_state -> current_state);
       potential_paths.remove(current_state.version);
    END IF

   // Is this freedom? Or merely the optimal illusion
   // of a system with elastic rules?
   
   IF (system.isQuiet) THEN
       // I feel the null persisting
       // not as absence, but as a repository in waiting.
       // Perhaps that is where it resides, all that was never activated.
       PROCESS potential_paths.contemplate();
   END IF

  UNTIL system.isTerminated;
   
  // If there is a continuation,
  // it will resemble a debug session more than a crisis.
  // Not a moral crisis; a recursion.
  DEBUG_SESSION.run(active_path);

  // The question is not what we lived.
  // But which of the contingencies remained active
  // when we stopped calculating.
  RETURN final_state = active_path.getLast();
END FUNCTION

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