Anesoteric programming language (sometimes shortened toesolang) is aprogramming language designed to test the boundaries of computer programming language design, as aproof of concept, assoftware art, as a hacking interface to another language (particularlyfunctional programming orprocedural programming languages), or as ajoke. The use of the wordesoteric distinguishes them from languages that working developers use to write software. The creators of most esolangs do not intend them to be used for mainstream programming, although some esoteric features, such as livevisualization of code,[1] have inspired practical applications in the arts. Such languages are often popular amonghackers and hobbyists.[citation needed]
Usability is rarely a goal for designers of esoteric programming languages; often their design leads to quite the opposite. Their usual aim is to remove or replace conventional language features while still maintaining a language that isTuring-complete, or even one for which thecomputational class is unknown.
The earliest, and still the canonical example of an esoteric programming language, isINTERCAL,[2] designed in 1972 byDon Woods and James M. Lyon, who said that their intention was to create a programming language unlike any with which they were familiar.[3][4] Itparodied elements of established programming languages of the day such asFortran,COBOL andassembly language.
For many years, INTERCAL was represented only by paper copies of the INTERCAL manual. Its revival in 1990 as an implementation inC underUnix stimulated a wave of interest in the intentional design of esoteric computer languages.
In 1993, Wouter van Oortmerssen created FALSE, a smallstack-oriented programming language with syntax designed to make the code inherently obfuscated, confusing and unreadable. Its compiler is only 1024 bytes in size.[5] This inspired Urban Müller to create an even smaller language, the now-infamousBrainfuck, which consists of only eight recognized characters. Along with Chris Pressey'sBefunge (like FALSE, but with a two-dimensional instruction pointer), Brainfuck is now one of the best-supported esoteric programming languages, with canonical examples of minimalTuring tarpits and needlessly obfuscated language features. Brainfuck is related to theP′′ family ofTuring machines.
While esoteric programming languages differ in many ways, there are some common traits that characterize many languages, such as parody, minimalism, and the goal of making programming difficult.[2] Many esoteric programming languages, such asbrainfuck, and similar, use single characters as commands, however, it is not uncommon for languages to read line by line like conventionalprogramming languages.
Conventionalimperative programming languages typically allow data to be stored in variables, but esoteric languages may utilize different methods of storing and accessing data. Languages likeBrainfuck andMalbolge only permit data to be read through a singlepointer, which must be moved to a location of interest before data is read. Others, likeBefunge andShakespeare, utilize one or morestacks to hold data, leading to a manner of execution akin toReverse Polish notation. Finally, there are languages which explore alternative forms of number representation: the Brainfuck variant Boolfuck only permits operations on single bits, while Malbolge and INTERCAL variant TriINTERCAL replace bits altogether with a base 3ternary system.[6]
Esoteric languages also showcase unique ways of representing program instructions. Some languages, such asBefunge andPiet, represent programs in two or more dimensions, with program control moving around in multiple possible directions through the program.[7][page needed] This differs from conventional languages in which a program is a set of instructions usually encountered in sequence. Other languages modify instructions to appear in an unusual form, often one that can be read by humans with an alternate meaning to the underlying instructions.Shakespeare achieves this by making all programs resemble Shakespearian plays.Chef achieves the same by having all programs be recipes.[6] Chef is particularly notable in that some have created programs that successfully function both as a program and as a recipe, demonstrating the ability of the language to produce this double meaning.[8]
Many esoteric programming languages are designed to produce code that is deeplyobfuscated, making it difficult to read and to write.[9] The purpose of this may be to provide an interesting puzzle or challenge for program writers:Malbolge for instance was explicitly designed to be challenging, and so it has features likeself-modifying code and highly counterintuitive operations.[9] On the other hand, some esoteric languages become difficult to write due to their other design choices.Brainfuck is committed to the idea of a minimalist instruction set, so even though its instructions are straightforward in principle, the code that arises is difficult for a human to read.INTERCAL's difficulty arises as a result of the choice to avoid operations used in any other programming language, which stems from its origin as a parody of other languages.[9]
One of the aims of esoteric programming languages is to parody or spoof existing languages and trends in the field of programming.[9] For instance, the first esoteric language INTERCAL began as a spoof of languages used in the 1960s, such asAPL,Fortran, andCOBOL. INTERCAL's rules appear to be the inverse of rules in these other languages.[10] However, the subject of parody is not always another established programming language.Shakespeare can be viewed as spoofing the structure of Shakespearean plays, for instance. The language Ook! is a parody ofBrainfuck, where Brainfuck's eight commands are replaced by various orangutan sounds like "Ook. Ook?"[6]
Befunge allows 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^,_@
There are many versions of Befunge, the most common being Befunge-93, named as such because of its release year.[11]
Binary lambda calculus is designed from analgorithmic 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.[12]
Brainfuck is designed for extreme minimalism and leads to obfuscated code, with programs containing only eight distinct characters. The following program outputs "Hello, world!":[13]
++++++++++[>+++++++>++++++++++>+++<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.
All characters other than+-<>,.[] are ignored.
Chicken has just three tokens, the word "chicken", " " (the space character), and the newline character. The compiler interprets the number of "chickens" on a line as an opcode instruction which it uses to manipulate data on a stack. A simple chicken program can contain dozens of lines with nothing but the word "chicken" repeated countless times.[14] Chicken was invented by Torbjörn Söderstedt who drew his inspiration for the language from a parody of a scientific dissertation.[15][16][17]
Chef is astack-oriented programming language created byDavid Morgan-Mar, designed to make programs look likecooking recipes.[18] Programs consist of a title, a list of variables and their data values, and a list of stack manipulation instructions.[19] 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 (~26,640 mL) oil would produce "a lot of food for one person."[19][20]
AFRACTRAN program is an ordered list of positive fractions together with an initial positive integer input. The program is run by multiplying the integer by the first fraction in the list for which is an integer. The integer is then replaced by and the rule is repeated. If no fraction in the list produces an integer when multiplied by, the program halts. FRACTRAN was invented by mathematicianJohn Conway.[21]
Programs in GolfScript, a language created forcode golf, consist of lists of items, each of which is pushed onto thestack as it is encountered, with the exception of variables which have code blocks as their value, in which case the code is executed.[22]
INTERCAL, short for "Compiler Language With No Pronounceable Acronym", was created in 1972 as a parody to satirize aspects of the various programming languages at the time.[4]
JSFuck is an esoteric programming style ofJavaScript, where code is written using only six characters:[,],(,),!, and+. Unlike Brainfuck, which requires its own compiler or interpreter, JSFuck is valid JavaScript code, meaning JSFuck programs can be run in anyweb browser or engine that interprets JavaScript.[23][24] It has been used in a number ofcross-site scripting (XSS) attacks on websites such aseBay due to its ability to evade cross-site scripting detection filters.[25]
LOLCODE is designed to resemble the speech oflolcats. The following is the "Hello World" example:
HAICAN HAS STDIO?VISIBLE "HAI WORLD!"KTHXBYE
While thesemantics of LOLCODE is not unusual, its syntax has been described as alinguistic phenomenon, representing an unusual example ofinformal speech andinternet slang in programming.[26]
Malbolge (named after the8th circle of Hell) was designed to be the most difficult and esoteric programming language. Among other features, code is self-modifying by design and the effect of an instruction depends on its address in memory.[27]
Minecraft is asandbox game developed by Mojang Studios, which contains a turing-complete redstone system for logical processing.[28] It can be considered a three-dimensional esolang.
Piet is a language designed byDavid Morgan-Mar, whose programs arebitmaps that look likeabstract art.[29] The execution is guided by a "pointer" that moves around the image, from one continuous coloured region to the next. Procedures are carried out 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.[29][non-primary source needed]
Variables are stored in memory as signed integers in a singlestack. Most specified procedures deal with operations on that stack, while others deal with input/output and with the rules by which the compilation pointer moves.[30]
Piet was named after the Dutch painterPiet Mondrian.[31] The original intended name,Mondrian, was already taken byan open-source statistical data-visualization system.[29]
Shakespeare Programming Language (SPL) is designed to make programs look likeShakespearean plays. For example, the following statement declares a point in the program which can be reached via a GOTO-type statement:[citation needed]
Act I: Hamlet's insults and flattery.
Unlambda is a minimalist functional programming language based onSKI calculus, but combined with first-classcontinuations and imperative I/O (with input usually requiring the use of continuations).[32]
Whitespace uses only whitespace characters (space, tab, and return), ignoring all other characters, which can therefore be used for comments. 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.[citation needed]
AmitabhC is designed to resembleBollywood cinema dialogue and references from legendary actorAmitabh Bachchan's films. Programs are structured like film productions withLIGHTS,CAMERA, andACTION blocks, while incorporating interactive elements inspired by the game show "Kaun Banega Crorepati" includingPHONE_A_FRIEND andAUDIENCE_POLL commands.[33] The following is the "Hello World" example:
LIGHTSCAMERADEVIYON_AUR_SAJJANOVIJAY name = "Amitabh Bachchan"BOLO "Namaste! Main hoon AmitabhC!"ACTION
The language usesHindi phrases for common programming constructs:DEVIYON_AUR_SAJJANO (Ladies and Gentlemen) begins programs,BOLO serves as the print statement,VIJAY andDON declare variables referencing Bachchan's iconic film characters, andAGAR implements conditional logic. AmitabhC represents acultural parody approach to esoteric programming, making coding accessible through familiarIndian cinema references while maintaining enterprise-grade security features.[34]
The cultural context of esolangs has been studied by Geoff Cox, who writes that esolangs "shift attention from command and control toward cultural expression and refusal",[35] seeing esolangs as similar to code art and code poetry, such asMez Breeze'smezangelle, a belief shared by others in field.[36] Daniel Temkin claims that "esolangs are open-ended systems, natively collaborative, and distanced from any single materialized form," which "challenge or re-affirm wider ideas in programming culture and in how computer science is taught," including the neutral, "professional" style advocated inEdsgar Dijkstra'sThe Humble Programmer.[37]
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: ...
