Esoteric programming language
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An esoteric programming language (sometimes shortened to esolang) is a programming language designed to test the boundaries of computer programming language design, as a proof of concept, as software art, or as a joke. The use of esoteric distinguishes these languages from programming languages that working developers use to write software. Usually, an esolang's creators do not intend the language to be used for mainstream programming, although some esoteric features, such as visuospatial syntax, have inspired practical applications in the arts. Such languages are often popular among hackers and hobbyists.
Usability is rarely a goal for esoteric programming language designers—often it is quite the opposite. Their usual aim is to remove or replace conventional language features while still maintaining a language that is Turing-complete, or even one for which the computational class is unknown.
- 1 History
- 2 Esoteric programming terms
- 3 Examples
- 4 Esolangs as art
- 5 In fiction
- 6 References
- 7 External links
The earliest, and still the canonical example of an esoteric language was INTERCAL, designed in 1972 by Don Woods and James M. Lyon, with the stated intention of being unlike any other programming language the authors were familiar with. It parodies elements of established programming languages of the day, such as Fortran, COBOL, and assembly language.
For many years INTERCAL was represented only by paper copies of the INTERCAL manual. The language's revival in 1990 as an implementation in C under Unix stimulated a wave of interest in the intentional design of esoteric computer languages.
In 1993, Wouter van Oortmerssen created FALSE, a small stack-oriented programming language, with syntax designed to make the code inherently obfuscated, confusing, and unreadable. It also has a compiler of only 1024 bytes. This inspired Urban Müller to create an even smaller language, the now-famous brainfuck, which consists of only eight recognized characters. Along with Chris Pressey's Befunge (like FALSE, but with a two-dimensional instruction pointer), brainfuck is now one of the most well-supported esoteric programming languages. These are canonical examples of minimal Turing tarpits and needlessly obfuscated language features. Brainfuck is related to the P′′ family of Turing machines.
Esoteric programming terms
A method of encoding programs, such that each substring of the encoding is an instruction to both:
- Locate the next instruction in a list, and
- Apply it to transform the current program state.
A single instruction always includes two sequential phases: choosing an operation, and executing it. The list of operations may either be static – as in reMorse or THRAT - or dynamic - as in reMorse4ever.
Here is an example based on reMorse or THRAT:
Select Next Operation in list Perform Operation
The paradigm of a language can fall into a number of categories, and these categories are used to get a general understanding of the way that a specific language operates. These include imperative languages such as brainfuck, in which instructions describe how to change data; functional languages such as Unlambda, in which data and code are more or less interchangeable and execution is the repeated application of functions to the results of other functions; and rewriting languages such as Thue, in which transformation functions are applied to an initial state.
A funge is an esoteric programming language which models its programs as metric spaces with coordinate systems (often, but not necessarily, Cartesian) and which execute instructions located at points in their program space by moving an instruction pointer (a position vector which indicates the currently executing instruction) through that space. Different instructions determine the direction in which the instruction pointer moves, and consequently, the sequence of instructions that is executed.
The current official standard for the behaviour of these programming languages is the Funge-98 specification. This specification is a generalisation of the semantics of the Befunge programming language, which has a two-dimensional toroidal topology. Languages which adhere closely to this standard, such as Unefunge (one-dimensional) and Trefunge (three-dimensional), are sometimes called funges, while more "distant relatives" which differ in significant respects, such as Wierd, are referred to as fungeoids.
For a deterministic language, if one is given the current state of a program, the next state can always be predicted. This is not true for a nondeterministic language. Most languages are deterministic, but some languages, such as Befunge, supply a built-in randomization instruction. Moreover, languages such as Java2k have only randomized instructions. Thus, getting even trivial programs to have a reliable output is often a monumental task.
Nondeterministic languages can be used to explore large search spaces, such as grammars, where exhaustive search is impractical. Random text generators such as the Dada Engine and rmutt are examples of this kind of nondeterminstic language.
More esoterically, nondeterministic algorithms have been employed in the theoretical investigation of hypercomputation.
Below are some characteristic examples of esoteric programming languages:
Ante is an esoteric programming language using only numbers and card faces as its syntax. A compacted "Hello World" example is as follows:
ArnoldC is an imperative programming language where the basic keywords are replaced with quotes from different Arnold Schwarzenegger movies. "hello world" looks like this:
IT'S SHOWTIME TALK TO THE HAND "hello world" YOU HAVE BEEN TERMINATED
Befunge and its like allow the instruction pointer to roam in multiple dimensions through the code. For example the following program displays "Hello World" by pushing the characters in reverse order onto the stack, then printing the characters in a loop which circulates clockwise through the instructions [>], [:], [v], [_], [,], and [^].
"dlroW olleH">:v ^,_@
Binary lambda calculus
Binary lambda calculus is designed from an algorithmic information theory perspective to allow for the densest possible code with the most minimal means, featuring a 29 byte self interpreter, a 21 byte prime number sieve, and a 112 byte Brainfuck interpreter.
Brainfuck is designed for extreme minimalism and leads to obfuscated code, with programs containing only eight distinct characters. The following program outputs "Hello World!":
Chef by David Morgan-Mar is a stack-oriented programming language designed to make programs look like cooking recipes. Programs consist of a title, a list of variables and their data values and a list of stack manipulation instructions. A joking design principle states that "program recipes should not only generate valid output, but be easy to prepare and delicious", and Morgan-Mar notes that an example Hello World program with "101 eggs" and "111 cups oil" would produce "a lot of food for one person."
FALSE is a stack-based language with single-character commands and variables. For example, 3 + 1 can be calculated by evaluating (λ x → x + 1)(3):
Programs in GolfScript consist of lists of items, each of which is pushed onto the stack as it is encountered with the exception of variables which have code blocks as their value, in which case the code is executed.
HAI CAN HAS STDIO? VISIBLE "HAI WORLD!" KTHXBYE
Malbolge (the 8th circle of Hell) was designed to be the most difficult and esoteric programming language.
One instruction set computer
A one instruction set computer is a machine which supports only one operation.
The "Hello World" example in Ook!:
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|Wikimedia Commons has media related to Piet (programming language).|
Piet is a language designed by David Morgan-Mar, whose programs are bitmaps that look like abstract art. The compilation is guided by a "pointer" that moves around the image, from one continuous coloured region to the next. Procedures are carried through when the pointer exits a region.
There are 20 colours for which behaviour is specified: 18 "colourful" colours, which are ordered by a 6-step hue cycle and a 3-step brightness cycle; and black and white which are not ordered. When exiting a "colourful" colour and entering another one, the performed procedure is determined by the number of steps of change in hue and brightness. Black cannot be entered; when the pointer tries to enter a black region, the rules of choosing the next block are changed instead. If all possible rules are tried, the program terminates. Regions outside the borders of the image are also treated as black. White does not perform operations, but allows the pointer to "pass through". The behaviour of colours other than the 20 specified is left to the compiler or interpreter.
Variables are stored in memory as signed integers in a single stack. Most specified procedures deal with operations on that stack, others with input/output and with the rules by which the compilation pointer moves.
Rocket is a programming language designed to be quick to write. With each function being a letter long, the lines tend to be very short.
Example Code (adds two numbers):
Shakespeare is designed to make programs look like Shakespearean plays. e.g. the following statement declares a point in the program which can be reached via a GOTO-type statement:
Act I: Hamlet's insults and flattery..
Whitespace uses only whitespace characters (space, tab, and return), ignoring all other characters. This is the reverse of many traditional languages, which do not distinguish between different whitespace characters, treating tab and space the same. It also allows Whitespace programs to be hidden in the source code of programs in languages like C.
Esolangs as art
Esolangs have begun to be interpreted as art or created with that point of view in mind. Geoff Cox writes that esolangs "shift attention from command and control toward cultural expression and refusal”, seeing esolangs as similar to code art and code poetry, such as Mez Breeze's mezangelle. Daniel Temkin describes brainfuck as "refusing to ease the boundary between human expression and assembly code and thereby taking us on a ludicrous journey of logic," exposing the inherent conflict between human thinking and computer logic. He connects programming within an esolang to performing an event score such as those of the Fluxus movement, where playing out the rules of the logic in code makes the point of view of the language clear.
A fictional programming language called ~ATH (pronounced "till death") appears in the webcomic Homestuck. The language consists entirely of loops of effectively interminable construction. The EXECUTE command is the only part of the language that can be used to execute anything, however, it can only be placed at the end of a loop, thereby delaying the execution for extremely long spans of time or, in some cases, forever. The loops can only be terminated by tying their ends to the "death" of a number of concepts importable from the language's library (for instance, if a loop's end is tied to the universe, it will end when the universe ceases to exist).
Unfortunately, any concept with a short lifespan such as a rapidly decaying particle is absent from the library, rendering ~ATH programs insufferably long and useless unless one exploits the code's loopholes, in which case it proves to be brutally efficient.
Apparently, ~ATH has reality-altering powers, as programs coded in it were used twice to explode the user's computer, once to put a curse on the user, everyone he ever met and (proactively) everyone he'll ever meet, and once to summon the time-travelling demon Lord English into the universe. The ~ATH language is seemingly color-sensitive (in the aforementioned curse program, black, red and blue text was used), but even more peculiar is the fact that the Lord English virus used a GIF animation as a subprogram. How this works is yet to be explained.
- McLean, A., Griffiths, D., Collins, N., and Wiggins, G. (2010). "Visualisation of Live Code". In Electronic Visualisation and the Arts, London: 2010.
- Eric S. Raymond (1996). The New Hacker's Dictionary. MIT Press. p. 258. ISBN 978-0-262-68092-9.
- Woods, Donald R.; Lyon, James M. (1973), The INTERCAL Programming Language Reference Manual, Muppetlabs.com, archived from the original on 2009-04-24, retrieved 2009-04-24
- Cozens, Simon (2005). Advanced Perl programming. O'Reilly Media. p. 269. ISBN 978-0-596-00456-9.
A final Acme curiosity, and one of my favourites, is Acme: :Chef, an implementation of David Morgan-Mar's Chef programming language. In Chef, programs are expressed in the form of recipes: ...
- Morgan-Mar, David (2011-03-24). "Chef". DM's Esoteric Programming Languages. Self-published. Retrieved 2014-06-28.
- Morgan-Mar, David (2014-06-28). "Chef Sample Program: Hello World Souffle". DM's Esoteric Programming Languages. Self-published. Retrieved 2014-06-28.
- Morgan-Mar, David (25 January 2008). "Piet programming language". Retrieved 18 May 2013.
- Geoff Cox (2013). Speaking Code: Coding as Aesthetic and Political Expression. MIT Press. p. 6. ISBN 978-0-262-01836-4.
- Cox, Geoff (2013). Speaking Code. Cambridge: MIT Press. p. 5.
- Temkin, Daniel (15 Jan 2014). "Glitch && Human/Computer Interaction". NOOART: The Journal of Objectless Art (1).
- Temkin, Daniel. "brainfuck". Media-N Journal (Spring 2013).