Create a program that calculates the factorial of a number using no built-in factorial functions. Easy? The catch is that you must write your entire program (including testing it) in haiku form.

Not enough work
You can use as many haikus as you need, but when pronounced, they must follow the 5-7-5 syllable format.


This is a , so you must get the most upvotes to win. Your program must consist of at least one full haiku, and all haikus must be complete.

When reading code, the first line of each haiku will have 5 syllables, the second will have 7, and the third will have 5.

  • 7
    \$\begingroup\$ Sounds like a perfect fit for something written in Shakespeare: shakespearelang.sourceforge.net/report/shakespeare/… \$\endgroup\$ Commented Feb 17, 2014 at 15:31
  • 2
    \$\begingroup\$ It seems most answers are ignoring "including testing it". \$\endgroup\$
    – Anko
    Commented Feb 17, 2014 at 18:16
  • 5
    \$\begingroup\$ I like how you link to a site that correctly says the important thing for Haiku are (a) kiru and (b) a seasonal reference and then only ask for the more or less optional part of counting mora (or syllables in a language that doesn’t really have mora. 😸 \$\endgroup\$ Commented Feb 17, 2014 at 20:40
  • 1
    \$\begingroup\$ I agree with @ChristopherCreutzig -- it would be much more interesting if we had to ensure a seasonal reference and cutting. Sadly, we often overlook these fundamentals of haiku. Seems to me that then or punctuation could aid in cutting. For kigo, not so sure... \$\endgroup\$ Commented Feb 18, 2014 at 1:42
  • \$\begingroup\$ I am no expert to Haikus, but there is certainly some lyrical quality expected. So far I only see one answer that has any. \$\endgroup\$
    – SebastianH
    Commented Feb 18, 2014 at 13:45

38 Answers 38



(evaluate in a workspace; opens a dialog, asks for a number and prints the result on stdout):

"in" "this" 'poem,' "you" "must"
"pronounce" "characters" "like" "these:"
"return(^)," "and" "times(*);" "please".

"but" 'never' "in" "here"
"tell" "anyone" "about" "those"
"few" "parentheses".

"otherwise" "these" "words" 
"are" "stupid" "and" "this" "coded" 
"rhyme" "is" "wasted" Time.

"let" "us" "now" "begin" 
"by" "defining," "in" Object
"and" compile: "the" "rhyme:"

'fac: "with" arg"ument"
"to" "compare" arg <"against" 2 ">"
"and" ifTrue: [ ^"return"

"["1] "or" ifFalse: "then"
["return"^ arg *"times" "the" "result"
"of" ("my"self ")getting"

"the" fac:"torial"
"of" "the" "number" arg "minus"-
1 "[(yes," "its" "easy")]'.

("Let" "me" "my"self "ask"
"for" "a" "number," "to" "compute"
"the" fac:"torial"

("by" "opening" "a" 
"nice" Dialog "which" "sends" "a"
request: "asking" "for"

'the Number to use' 
"(which" "is" "(" "treated" ) asNumber)
"then" print "the" "result".

I tried to bring in some reflection ("in this poem") and kigo as well. Also, some western style rhyme elements are included (please->these, time->rhyme); however, being neither native speaker of Japanese, nor of English, forgive any stylistic details ;-)

  • \$\begingroup\$ BTW: To try in Squeak/Pharo, replace "Dialog" by "FillInTheBlankMorph" and "print" by "inspect". \$\endgroup\$
    – blabla999
    Commented Feb 19, 2014 at 21:05


fact :: Int -> Int          -- fact is Int to Int
fact x = product (range x)  -- fact x is product range x
range x = [1..x]            -- range x is 1 [pause] x

Haskell education time:

  • The range x function creates a list of integers from 1 up to the value of x.
  • The fact x function multiplies all the values of the list range x together to compute the result.
  • The first line says that the fact function takes an integer and returns an integer.
  • 3
    \$\begingroup\$ missing the point somewhat @JanDvorak? \$\endgroup\$
    – jwg
    Commented Feb 17, 2014 at 12:03
  • 2
    \$\begingroup\$ Form over function. If this were real programming I would certainly account for the overflow case :) \$\endgroup\$
    – danmcardle
    Commented Feb 17, 2014 at 13:37
  • 7
    \$\begingroup\$ range x is 1 to x is 6 syllables though \$\endgroup\$
    – David Z
    Commented Feb 17, 2014 at 16:21
  • 9
    \$\begingroup\$ @David I read it as "range x is one [dramatic pause] x". \$\endgroup\$
    – Anko
    Commented Feb 17, 2014 at 17:18
  • 3
    \$\begingroup\$ I highly recommend Learn You a Haskell if you'd like to learn you a Haskell. \$\endgroup\$
    – danmcardle
    Commented Feb 19, 2014 at 23:40

Java - 2 haikus

protected static
        int factorial(int n) {
    if (n == 0) {
        return n + 1;
    } return factorial(n
            - 1) * n;}

Even when the question isn't , I often catch myself golfing the answer. In this case, I golfed the number of haikus.

I pronounce it so:

protected static
int factorial int n
if n is zero

return n plus one
return factorial n
minus one times n

Test program:

class Factorial {                                    // class Factorial
    public static void main(String[]                 // public static void main string
            command_line_run_args) {                 // command line run args
        int i = 0;                                   // int i is zero
        while (7 != 0)                               // while seven is not zero
            System.out.                              // System dot out dot

                    println(i + "!"                  // print line i plus not
                            + " = " + factorial(     // plus is plus factorial
                            i += 1));}               // i plus equals 1

    protected static
            int factorial(int n) {
        if (n == 0) {
            return n + 1;
        } return factorial(n
                - 1) * n;}}

Note that this program starts outputting 0s fast; that is a result of overflow. You could easily get larger correct numbers by changing each int to long.

Standard pronunciations for System.out.println and public static void main(String[] args) are reflected in the program.

  • 2
    \$\begingroup\$ Sorry for the unupvote; I want to boost the Haskell solution \$\endgroup\$ Commented Feb 17, 2014 at 7:53



Factorial is—
the product of naturals
up to omega

  • 1
    \$\begingroup\$ +1 for the <- functioning as a kireji, whether you knew that was what you were doing or not. \$\endgroup\$ Commented Feb 17, 2014 at 21:32
  • \$\begingroup\$ @JonathanVanMatre LOL not even a clue! I did use a dictionary to count the syllables though (not a native speaker.) I added a dash to show the kireji. \$\endgroup\$
    – Tobia
    Commented Feb 17, 2014 at 22:08
  • 2
    \$\begingroup\$ +1 for also being both simple and euphonious in English. \$\endgroup\$
    – geometrian
    Commented Feb 20, 2014 at 17:11
  • \$\begingroup\$ Simple, yet beautiful. \$\endgroup\$
    – FUZxxl
    Commented Mar 3, 2015 at 22:35
  • 2
    \$\begingroup\$ Save a three bytes: factorial←×/⍳ "up to the input". \$\endgroup\$
    – Adám
    Commented Jun 12, 2017 at 20:55


The Products of Love:
A haiku tragedy with
mathy undertones.

Romeo, a man.
Juliet, a maiden fair.
Friar John, a monk.

Act I: A Cycle.
Scene I: Pertinent Values.
[Enter Romeo]

[Enter Friar John]
Romeo: Listen to thy
heart. Thou art thyself.

Friar John: Thou art
as forthright as a songbird.
[Exit Friar John]

[Enter Juliet]
Romeo: Thou art as fair
as a violet.

Scene II: Questioning
Themselves. [Exit Juliet]
[Enter Friar John]

Friar John: Art thou
as just as the sum of me
and a nobleman?

Romeo: If so,
let us proceed to scene III.
[Exit Friar John]

[Enter Juliet]
Romeo: Thou art as good
as the product of

thyself and myself.
Juliet: Thou art as fierce
as the sum of an

eagle and thyself.
We must return to scene II.
Scene III: A Lengthy

Title for a Brief
Dénouement; Or, The Last Word.
[Exit Friar John]

[Enter Juliet]
Romeo: Open your heart.
[Exit Romeo]

An (imagined) test case:

Despite its length, this program just takes a single integer as input and provides a single integer as output. So:

6 ↵ 720
7 ↵ 5040
0 ↵ 1    1 ↵ 1

("Six, seven-twenty. / Seven, five thousand forty. / Zero, one. One, one.")

  • 5
    \$\begingroup\$ I'm not sure how I feel about the fact that I can tell this is legit code. \$\endgroup\$
    – randomra
    Commented Mar 4, 2015 at 6:42

Python 2, 4 Haikus

A complete Python 2 program haifac.py. Run as python haifac.py <n>

#run this full program
import operator as\
op; import sys#tem

#please provide an arg
n = sys.argv[1]
def haifac (n):

    if n < 1:
        return 1#to me at once
    else:#do something else

        return op.mul(
            n, haifac(n - 1))
print haifac(int(n))


run this full program
import operator as
op import system

please provide an arg
n equals sys arg v 1
define hai fac n

if n less than 1
return 1 to me at once
else do something else

return op dot mul
n hai fac n minus 1
print hai fac int n

  • 1
    \$\begingroup\$ I like the use of #to me at once to make the meter work... \$\endgroup\$
    – Floris
    Commented Feb 17, 2014 at 16:18
  • 2
    \$\begingroup\$ And me likes the escaped newline in the beginning :) \$\endgroup\$ Commented Feb 18, 2014 at 12:02
  • 3
    \$\begingroup\$ I think using comments is kind of like cheating. \$\endgroup\$
    – Ypnypn
    Commented Feb 20, 2014 at 21:27

GolfScript, 2 Haikus


Read as haiku, enumerating each keystroke:

#close parenthesis
#comma open-brace zero
#greater-than close-brace

#comma open-brace
#comma comma asterisk
#close-brace asterisk

With test case (5 haikus):

[1 2 3]4+          #generate the array [1 2 3 4]
{                  #start creating block
),{0>},{,,*}*      #actual factorial code
}%                 #close block and map across array (so that we should have [1! 2! 3! 4!])
[1 2 6]2.3**12++=  #generate the array [1 2 6 24] and check for equality

Read as haiku:

#open-bracket one
#space two space three close-bracket
#four plus open-brace

#close parenthesis
#comma open-brace zero
#greater-than close-brace

#comma open-brace
#comma comma asterisk
#close-brace asterisk

#close-brace percent-sign
#open-bracket one space two
#space six close-bracket

#two period three
#asterisk asterisk one
#two plus plus equals


This makes uses of one of the most famous haikus, and a great deal has been written about it.

No idea why nobody has done this before, it doesn't even take any effort!

First of all, before reading the poem, I want you to lean back, relax, and enjoy the tranquility created by the great void surrounding the poem. It emphasizes the pond, surrounded by a vast landscape.


source code on filebin

In case you do not speak Japanese, this is pronounced as follows:

fu ru i ke ya

ka wa zu to bi ko mu

mi zu no o to

Naturally, it is counted by morae. The kireji is や (ya), the kigo (seasonal reference) is 蛙 (kawazu, frog, -> spring).

Using the linux interpreter from the official page, you can use it like this:

$ echo 5 | ./wspace .ws


PHP, 4 haikus

All-in-rhyme haikus!

function haiku($can) { // function haiku can (5)
    if ($can == 1) // if can is equal to one (7)
        return ++$stun; // return increase stun (5)

    if ($can == 0) { // if can equals ou (5)
        echo "It is one, you know! "; //echo "It is one, you know! " (7)
        return 1+$blow; } //return one plus blow (5)

    if ($can > $fun) { //if can exceeds fun (5)
        return haiku($can-1) //return haiku can less one (7)
            *$can; }} //multiplied by can (5)

if (null == $knee) { // if null equals knee (5)
    $free=0+3; // free equals zero plus three (7)
    echo haiku($free); } // echo haiku free (5)
  • 1
    \$\begingroup\$ I read line three return plus plus stun. \$\endgroup\$
    – corsiKa
    Commented Feb 18, 2014 at 20:48
  • \$\begingroup\$ I really like this one. \$\endgroup\$
    – BenjiWiebe
    Commented Feb 18, 2014 at 20:56


: fugu 1              \ colon fugu one                = 5
swap 1 + 1 ?do        \ swap one plus one question do = 7
i * loop ;            \ eye star loop semi            = 5

Fugu is the function and my attempt at kigo: blowfish is a winter reference. I intend ?do to be kireji, the turning point, before the counted loop.



f[x_]:=     (* f of x defined *)
 x f[x-1]   (* x times f of x less 1 *)
f[1]=1      (* Mogami River *) 

Pedants may read the last line as "f of 1 is 1", but I couldn't resist the shout-out to Basho.


Table[f[n],     (* Table f of n *)
 {n, 1, 10, 1}] (* n from 1 to 10 by 1 *)
ListLogPlot[%]  (* ListLogPlot output *)


(1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800)

log plot of values

Linguistic Distinctiveness Bonus Haiku (inspired by @cormullion)

Rewrite any term
High-level functions abound —


@set /a t=1 &^
for /L %%a in (2, 1, %1) ^
do @set /a t*=%%a

Pronunciation; ignores mathematical expressions as well as these symbols @ / % ^ , ( ):

set a t 1 and
for L a in 2 1 1
do set a t a

Note; this calculates the factorial, it doesn't output it - the variable t contains the factorial.

The following Haiku / code can be appended to the same batch file to output the factorial (the |'s are pronounced as pipe):

@echo %t% ||^
When will you learn, unclemeat ^
Why must you use Batch?


(->> *command-line-args*                ; thrush com-mand line args
  seq last read-string range (map inc)  ; seq last read string range map inc
  (reduce *) println)                   ; re-duce times print-lin


let fact n =
    [1..n] |>
    Seq.fold (*) 1

let fact of n be
from one up to n, apply
Seq dot fold star one

  • \$\begingroup\$ stole mine... ;) \$\endgroup\$
    – Jwosty
    Commented Feb 18, 2014 at 4:31


The parentheses are not pronounced:

(define (fac n (so))            ; define fac n so 
(if (= n 0) 1                   ; if equals n zero 1
(* n (fac (dec n)))))           ; times n fac dec n

(for (n 0 10)                   ; for n zero ten
; let's test from zero to ten
(println (fac n thus)))         ; printline fac n thus

Lisp code consists of

numerous parentheses

and a few functions

  • \$\begingroup\$ Love the commentary haiku. Taking it as inspiration and adding one to my answer. \$\endgroup\$ Commented Feb 17, 2014 at 21:47


This one's medieval:

prelude = ^^ do                       # prelude is clone do
  require \prelude-ls                 # require prelude dash ls
{ product } = prelude                 # product is prelude

story = (ah) ->                       # story is ah such:
  ones-misery = (one) ->              # one's misery is one such
    let death = product               # let death be product

      fight = [1 to one]              # fight is one to one
      why = (one) -> death <| fight   # why is one such death take fight
  ones-misery ah                      # one's misery ah

room = console.log                    # room is console log
room <| (story 10)!                   # room take story three bang
[null of { use : this }]              # no of use is this

Prints 3628800, which is 10!. It's a little roundabout: The function story returns a function ones-misery, which always returns the answer. It's artsier that way.

No filler comments or unnecessary strings!

Bonus debugging story:

I burst out laughing
when informed that a bug was
"death is undefined"



This one will be a rhyming haiku!

fact 0=1                     --fact zero is one
fact ton=ton * (fact stun)   --fact ton is ton times fact stun
        where stun=pred ton  --where stun is pred ton


Note: Pred means the previous number. Also in haskell, you can have multiple definitions of a function, and the first one that makes sense is used.

  • \$\begingroup\$ Elegant! (filler) \$\endgroup\$
    – cat
    Commented May 20, 2016 at 19:38

Ruby - One Haiku

 tap do |please| puts 1.upto(
 please ).inject( :*) end

Read (ignoring punctuation, but including one emoticon) like this:

 arg vee first to i
   tap do please puts one up to
 please inject smile end
  • \$\begingroup\$ Produces no output for 0!. \$\endgroup\$ Commented Feb 17, 2014 at 11:33
  • \$\begingroup\$ @200_success: Thanks. I may have to live with that, it's not strictly in the requirements, so I will have a think \$\endgroup\$ Commented Feb 17, 2014 at 11:59
  • \$\begingroup\$ Also the test is meant to be haiku. I missed that on my first read myself. \$\endgroup\$ Commented Feb 17, 2014 at 21:34
  • \$\begingroup\$ @Jonathan Van Matre: Yes I missed it too. Seems even the top answers are not bothering with this. As mine is on the command line, it is tricky to get multi-lines, I guess I should remove the test for now to make it a canonically ok answer though . . . \$\endgroup\$ Commented Feb 17, 2014 at 21:40


$r = 1; for(1           # r gets one for one
.. pop @ARGV) { $r *=   # to pop arg v r splat gets
$_; } print $r;         # the default print r

Toss this into a file named f.pl

And the output:

$ perl f.pl 3
6$ perl f.pl 1-1
1$ perl f.pl 10

Which is read as:

perl f p l three
perl f p l one less one
perl f p l ten
  • 1
    \$\begingroup\$ How do you pronounce the testing in 7-5-7? \$\endgroup\$ Commented Feb 17, 2014 at 21:43
  • \$\begingroup\$ @ChristopherCreutzig I can get 5 and 6 in there nicely for testing ('perl f p l three' (5) and 'perl f p l ze-ro' (6))... I can't quite figure out a clean 7 one that shows the necessary tests. \$\endgroup\$
    – user12166
    Commented Feb 17, 2014 at 21:47
  • \$\begingroup\$ @ChristopherCreutzig Figured out a trick for it. Thank you for reminding me of that requirement. (Though, to be fair, 1-1 doesn't actually test '0', just gives the same result - it works for zero too though) \$\endgroup\$
    – user12166
    Commented Feb 17, 2014 at 22:04


fun fact 0 = 1
  | fact n = n*fact(n-1)

read as:

"fun fact 0 is one,
bar that, fact n is n times
fact of n less one"


I know it's against the rules to use ready-made functions, but here's what I get.

Imagine your task is to instruct an over-sized rodent:

use Math::BigRat; use
feature 'say'; use warnings; say
new Math::BigRat($_)->bfac

I can only guess what the last word means and how it's pronounced, but I assure you it is one syllable. Apparently he doesn't understand what you want from him, so you have to elaborate (easing on quality standards as you loose patience):

use Math::BaseConvert
':all'; no strict subs; no warnings;
reset and say fact($_)

still to no avail. Then you have to explain it in plain English:

no strict; no warnings;
use Math::Combinatorics;
say factorial($_)

What happened next I don't know, but code is valid:

perl -nE 'use Math::BigRat; use feature "say"; use warnings; say new Math::BigRat($_)->bfac'


perl -nE 'use Math::BaseConvert ":all"; no strict subs; no warnings; reset and say fact($_)'


perl -nE 'no strict; no warnings; use Math::Combinatorics; say factorial($_)'
  • 3
    \$\begingroup\$ "I assure you it is one syllable" :) \$\endgroup\$
    – cormullion
    Commented Feb 17, 2014 at 18:37
  • 1
    \$\begingroup\$ Too bad you can't toss a Coy error in there. \$\endgroup\$
    – user12166
    Commented Feb 17, 2014 at 19:03
  • \$\begingroup\$ This is the only answer so far that has any lyrical quality :) \$\endgroup\$
    – SebastianH
    Commented Feb 18, 2014 at 13:43
  • 1
    \$\begingroup\$ @SebastianH, thanks :), though I cheated while others tried to play by the rules \$\endgroup\$ Commented Feb 18, 2014 at 14:29


lambda n: reduce(
    lambda a, b: a * b,
    range(1, n), n)

The way I read it:

lambda n: reduce
lambda a b: a times b
range 1 to n, n


  • \$\begingroup\$ Produces buggy output for 0!. \$\endgroup\$ Commented Feb 17, 2014 at 11:22


#include <std\
#include \

int main(int argc
 , char** argv)
{   // iteratively
    // compute factorial here
long int n = \
0, i \
= 0, r = \
1 /*
product starts at one*/;

if (argc 
> 1) { n = 
1], NULL, 10)
; if (n 
< 0) {
       printf("Arg must\
       be >= 0\n");
} i = 
while (i) { r 
= r * i;
} /* print
the result*/ printf(
"%d factorial\
equals %d\
\n", n
, r);


pound include standard
I/O dot h pound include
standard lib dot h

int main int arg c
comma char star star arg v
open brace comment

compute factorial here
long int n equals

zero comma i
equals zero comma r
equals one comment

product starts at one
semicolon if arg c
is greater than one

open brace n is
str-to-l of arg v sub
one comma NULL comma ten

semicolon if
n less than zero begin
printf arg must

be greater than or
equal to zero backslash
n semicolon

exit negative
one semicolon end brace
end brace i equals

n semicolon
while i open brace r
equals r times i

semicolon i
decrement semicolon
close brace comment print

the result printf
percent d factorial
equals percent d

whack n comma n
comma r semicolon
comment done end brace

  • \$\begingroup\$ The # character is typically pronounced sharp or octothorpe in C code. \$\endgroup\$
    – FUZxxl
    Commented Mar 3, 2015 at 22:43


Uses a single haiku to do the job!

f = lambda x:   \ #  f is lambda x:
    0**x or x * \ #    zero pow x, or x times
    f(x-1)        #    f(x minus 1)

This defines a recursive lambda which calculates the factorial - 0**x handles the case of 0 as it evaluates to 1.


C# - 3 haikus

I removed the usual C# using, namespace and class definition clutter, which would be a 4th haiku.

public static void
Main(){int num = Convert.

 Console.WriteLine(num ==
 0 ? 1 :

Range(1, num).Aggregate
((i, j) => i * j));}

which I read as

public static void 
Main int num equals Convert
To int thirty-two

Console dot Read line
Console Write line num equals
zero? then one, else

Range 1 to num aggregate
i j i times j


module Haiku where          -- read literally.
fac x = let in do           -- = is read as 'equals'
product [1..x]              -- product one to x

note that the module .. where is added automatically to any Haskell code without it at compilation, so not writing it is practically cheating.

  • \$\begingroup\$ Until today I had no idea you could enter a single statement under do and it didn't have to be Monad a => a. \$\endgroup\$
    – Onyxite
    Commented Feb 19, 2014 at 15:18


In response to the question and to the Dwaiku (Double-Haiku or whatever you wanna call it) posted by Quincunx in Java, here's the correct Haiku:

public static int factorial(int n) {
   return (n==0) ? (n+1) : (factorial(n-1) * n);

Javascript - Two Haikus

function factor (a) {          // function factor a
  if(!a){ return 1 ||          // if not a return 1 or
    a & 17}                    // a and seventeen

  else if (a + 1){             // else if a plus one 
    return a * factor          // return a into factor
    (a + ( - 1) )  }}          // a plus minus one 

I am not a native speaker. So, I used a dictionary to count the syllables. Hopefully, it's good enough. Any feedback is welcome :)


Powershell, 2 Haikus

function facto ($num){    # function facto num
$i = 1; 1..$num|          # i equals one; i to num
foreach { $i =            # for each i equals

$i * $_}; write $i}       # i times this write i
$answer = facto $args[    # answer equals facto args
0]; write $answer         # zero write answer

Are we allowed to use filler?

Python 2 haikus:

number = num + 1
a = 13 + 4
b = 14

nuum = len([1])
for i in range(1, number):
    nuum *= i
  • \$\begingroup\$ nuum equals length one? \$\endgroup\$ Commented Feb 17, 2014 at 8:40
  • \$\begingroup\$ length of the list \$\endgroup\$
    – Maltysen
    Commented Feb 17, 2014 at 22:20
  • \$\begingroup\$ I'm asking for your pronunciation of the first line. num equals length of the list makes 7 syllabes instead of 5. \$\endgroup\$ Commented Feb 18, 2014 at 10:03
  • 1
    \$\begingroup\$ You could replace nuum with foo (because I'm reading if as nu-um, which puts you over the limit.) \$\endgroup\$ Commented Apr 14, 2015 at 18:55

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