Although languages like APL, Prolog and COBOL might seem unusual to many of today’s programmers, they are serious languages developed to address a specific requirement or a particular model of programming. We’re looking here at those languages that have been designed, first and foremost, to be odd. Referred to as esoteric programming languages, some are intended as jokes, some as parodies of other languages, whereas others were designed to be downright strange.
Esoteric programming languages: is there room in your brain for these nutty devices?
Bizarre or not, though, all of them truly are programming languages in the sense that they really can be used to provide instructions to your PC. Our intention here isn’t to show you a lot about any one language – after all, you’re not exactly going to be using them for genuine programming projects – but to look at three of then, fairly briefly, to give you a feel for the variety of esoteric languages.
INTERCAL
The names of programming languages are often acronyms that give some clue as to their purpose. So BASIC is Beginners All-purpose Symbolic Instruction Code, COBOL is COmmon Business Oriented Language and FORTRAN is FORmula TRANslation. So you start to get a feel for INTERCAL when you read in the manual (which you can find at www.muppetlabs.com/~breadbox/intercal/intercal.txt) that its full name is “Compiler Language With No Pronounceable Acronym, which is, for obvious reasons, abbreviated INTERCAL”. It was designed with the aim of being as obtuse as humanly possible, mainly so you that you can amaze your fellow programmers by your ability to do something useful in this bizarrely complicated language which was designed specifically to have nothing at all in common with any other major language.
Ironically, since our stated aim is to show you how to program in esoteric languages, we’ve not even going to try with INTERCAL. Instead we’ll show you how to use the INTERCAL-J compiler using a sample program provided and then we’ll leave you to peruse the manual. We suggest you do this in a darkened room and clear a week or two from your diary before you start. If you consider this a dereliction of our duties, take a look at the INTERCAL program below, which has been provided to illustrate how fiendishly involved even a simple program can be. Its purpose is to read in 32-bit unsigned integers, treat them as signed, 2s-complement numbers, and print out their absolute values, terminating if the absolute value is zero. A comparable APL program runs to 16 characters.
DO (5) NEXT
(5) DO FORGET #1
PLEASE WRITE IN :1
DO .1 <- 'V":1~'#32768$#0'"$#1'~#3
DO (1) NEXT
DO :1 <- "'V":1~'#65535$#0'"$#65535'
~'#0$#65535'"$"'V":1~'#0$#65535'"
$#65535'~'#0$#65535'"
DO :2 <- #1
PLEASE DO (4) NEXT
(4) DO FORGET #1
DO .1 <- "'V":1~'#65535$#0'"$":2~'#65535
$#0'"'~'#0$#65535'"$"'V":1~'#0
$#65535'"$":2~'#65535$#0'"'~'#0$#65535'"
DO (1) NEXT
DO :2 <- ":2~'#0$#65535'"
$"'":2~'#65535$#0'"$#0'~'#32767$#1'"
DO (4) NEXT
(2) DO RESUME .1
(1) PLEASE DO (2) NEXT
PLEASE FORGET #1
DO READ OUT :1
PLEASE DO .1 <- 'V"':1~:1'~#1"$#1'~#3
DO (3) NEXT
PLEASE DO (5) NEXT
(3) DO (2) NEXT
PLEASE GIVE UP
So to business and in particular we’re going to compile and run a program that prints out prime numbers. J-INTERCAL runs from the command prompt so Select Run… from the Windows Start menu, enter ‘cmd’ into the Open box in the Run window before clicking on OK. Then, at the prompt in the command line window, type ‘cd c:\jintercal-0.12\samples\’ and you’ll notice that the prompt will change to reflect the new default directory which is, in fact, the one where you’ll find an INTERCAL source file called primes.i. To compile it, type ‘Java intercal.Compile primes.i’, noting the capital C in ‘Compile’. All being well it will create the Java class file primes.class that you’ll be able to see if you type ‘dir’ at the prompt to list all the files in the folder. Now to run it, type ‘Java primes’ and you’ll see prime numbers flash down the screen expressed as Roman numerals which is INTERCAL’s standard form of output.
Brainfuck
INTERCAL programs are long and convoluted, aided and abetted, to no small degree, by the requirement to write polite programs with sufficient PLEASE statements included. Not so with the inappropriately sweary Brainfuck. Its programs couldn’t be more different. The aim was to implement a language with the smallest possible compiler – the compiler we’re using is just over 2Kbytes in length (yes, Kbytes, not Mbytes) and the record is somewhat less than 200 bytes. This required simplicity and despite the fact BF is Turning complete, meaning that it can perform any computation that “serious” languages can perform, it has just eight instructions, each of which is represented by a single character. That doesn’t make for the most readable program – so again you’ll reach guru status if you can master it – but it does mean that we can teach you the language in its entirety.
There is no concept of named variables, as there is in most languages. Instead BF has a string of 8-bit memory locations and a pointer that records which of those locations the current instruction will operate on. Initially all the locations contain zero and the pointer is initialized to the left-most location. With that bit of background we can now introduce the eight instructions, which are:
+ Increment the value at the pointer
- Decrement the value at the pointer
> Move the pointer to the right
< Move the pointer to the left
[ Start of loop
] End of loop (exit if value at pointer is zero)
, Input an ASCII character and store it at the pointer
. Print the ASCII character at the pointer
Of course a simple instruction set invariably means a complicated program so the simplest of operations, that might be achievable in a single instruction of a conventional language, can take dozens of instructions in BF. As an example we’re going to create a program that accepts two single digit numbers as its input and outputs their sum. The program to do this is as follows and, despite the fact it has 30 instructions, it still only works correctly if the answer is represented by a single decimal digit:
, > + + + + + + [ < - - - > - ] , [ < + > - ] < .
Your first job is to create a file containing the code showed above using Notepad. Since the space character isn’t a valid instruction it’s ignored and although we put a space between each character to make the code easier to read, you can leave them out. Note also that the full-stop at the end is part of the program. Call the file add.b and place it in the c:\bfd100 folder. Actually Notepad will try to give the file the name “add.b.txt” so you’ll have to rename it in Windows Explorer.
Now start up the command line window and change the directory to c:\bfd100\ – if you’re not familiar with command line prompts we did something very similar when we started to use INTERCAL. At the prompt type ‘bfd add.b’. BF will respond with the message ‘File assembled’, and if you do a directory listing you’ll see that the file add.com has indeed been created. This is a DOS executable file so all you have to do to execute it is to type ‘add’ at the prompt. Now type in your two one-figure numbers (with no space or punctuation between them) and the program will display their sum, immediately after the input, again without a separating space.
Now a slight aside. To be quite honest, of the three languages here, BF is the only one that you might want to delve into. After all, it’s quite an interesting language in its own way, in contrast to the others which are, quite frankly, plain dumb, and that’s being charitable. So to start you on your voyage of discovery, let’s see how the simple program above manages to add together two numbers.
The comma reads the first of the two figures and places it where the pointer is positioned which is, initially, in the left most memory location. However, the value read is an ASCII character which, for the figures 0 to 9, are the codes 48 to 57 so, to yield the actual number represented, we need to subtract 48. That’s achieved with the rest of the code up to but not including the second comma. It does that by moving the pointer to the right and incrementing that memory location six times so that it contains the value 6 which will then be used as a loop counter. Next it enters a loop that decrements the ASCII code eight times and the loop counter once. Since this loop will execute eight times, and each time it will subtract six from the ASCII code, when it does exit 48 will have been subtracted from the value input. The second comma inputs a second ASCII code which, because of the position of the pointer, will be stored one location to the right of the first value and again this will be used as a loop counter. The second loop causes the first value to be input (now decremented by 48) to be incremented as many times as the value of the second ASCII code input. When the loop exits, the value in the left-hand memory location (which is a valid ASCII value for a digit since we only subtracted 48 from one of the input values) is printed out.
BF commands might be terse but that doesn’t mean that programs can’t be made readable. Since all but the eight characters representing instructions are ignored, comments can be placed anywhere, as the following program shows.
===INPUT NUMBER===
+ cont=1
[
- cont=0
>,
======SUB10======
----------
[ not 10
<+> cont=1
=====SUB38======
----------
----------
----------
--------
>
=====MUL10======
[>+>+<<-]>>[<<+>>-]< dup
>>>+++++++++
[
<<<
[>+>+<<-]>>[<<+>>-]< dup
[<<+>>-]
>>-
]
<<<[-]<
======RMOVE1====
<
[>+<-]
]
<
]
Java2K
Unlike our previous two languages which were supported by compilers, Java2K is implemented as an Integrated Development Environment (so it’s a bit of a mystery why it’s referred to as DIE for Win32 instead of IDE). But before you get too excited, this doesn’t mean a fancy integrated editor and all the works, it just means that immediately after compiling the code it runs it. To start it just double click on the Java2K.exe icon in the c:\java2k\ folder it’ll open in a command line window and announce its presence with the rather puzzling statement “ELVIS HAS LEFT THE BUILDING AT 0.0.1900 <chair>:”. To see it in action just type the name of one of the sample Java2K programs supplied, say “26”, and you’ll see the output which, in this case, is the letter “F”. Having seen something of the astonishing power of this remarkable language you’ll be eager, no doubt, to try out more of the sample programs. However if, for the moment, you can get over your understandable excitement, we’ll first take a look at Java2K behind the scenes.
Like INTERCAL and most other languages, but unlike BF, Java2K has operators that work on variables. Like BF, Java2K is obscure in the extreme but whereas in the case of BF that was by necessity (i.e. to achieve the goal of producing a tiny compiler), in the case of Java2K it’s by design. First of all, where most languages use decimal numbers, perhaps with the option of binary, octal or hexadecimal, Java2K uses numbers to the base 11 which, as the manual points out, is close enough to decimal. Because base 11 numbers require an additional digit to the usual 0-9, Java2K uses 0-9 plus space. The upshot of this is that since a space will be interpreted as the number ten, spaces can’t be used just to make programs more readable. Second, function names are numbers rather than words, and so too are the names of variables. So you can forget, for example, of using meaningful variable names such as “Total” or sensible instruction names such as “Print”. In the case of this latter instruction Java2K uses the instruction “1 1 “ (note the two spaces, after all this is a base 11 number) instead. And finally, on the subject of obscuration, because numbers are interpreted as functions or variables, you can’t use them as numerical constants. Instead, if you want to refer to the number one, you have to use some function that will produce 1 as its output. The classic way of doing this is to use the code “11 6/*/_\”. If we point out that “11 6” is the divide function, “*” returns a random number, “_” repeats the previous argument, “/” is a separator and “\” is an end-of-instruction marker, it should be clear that this will produce a 1. Surprisingly, then, this statement isn’t quite correct as we’re about to see.
1 1 /125 /131 /119 /125 /11 6/*/_\/_\/125 /13 2
/*/_\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2
/*/_\/_\\/119 /125 /11 6/*/_\/_\/125 /13 2/*/_\
/_\\\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/
_\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/
_\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/
_\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/
_\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/
_\/_\\/119 /125 /11 6/*/_\/_\/125 /13 2/*/_\/_\
\\\\\\\/*\1 1 /125 /119 /11 6/*/_\/13 2/*/_\\/
125 /131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/_\
/_\\/119 /125 /11 6/*/_\/_\/125 /13 2/*/_\/_\\\
/125 /131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/_
\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/_
\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/_
\/_\\/131 /119 /125 /11 6/*/_\/_\/125 /13 2/*/_
\/_\\/119 /125 /11 6/*/_\/_\/125 /13 2/*/_\/_\\
Using the Java2K IDE (sorry, DIE) run the program 13 which is supposed to display “Hello, World”. We’ve included a small chunk of it above. Run it a few times and you’ll probably notice something odd – it doesn’t always get it right. The reason for this is that unlike virtually any other language, Java2K is a probabilistic language rather than a deterministic one so all its functions generate the “correct” answer only 90% of the time; for the remaining 10% it will give a random result. So the method of generating a one that we saw above only has a 90% chance of success. And that’s just for generating a one. The obvious way of generating a two is to add two ones together using the code “125 /11 6/*/_\/_\” but we’re now introducing another instruction that also has a 90% chance of success so the combined likelihood of getting the expected result drops to 81%. In this light of this you might find it surprising that the program 13 manages to produce “Hello, world” as often as it does.
The fact is that there are clever tricks that Java2K programmers can use to improve a program’s success rate but the result is that even the simplest of programs can be extremely long, not to mention virtually incomprehendable. As proof of this why don’t you take a look at program 13 using Notepad. Having done so we suggest that you use the experience to convince yourself that there are better ways of spending your time than attempting to learn Java2K. If you choose to ignore this advice you’ll find the programming manual, in all it succinct glory, at www.p-nand-q.com/humor/programming_languages/java2k/manual.html but we won’t be responsible for the consequences.
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