LOLCODE is an esoteric programming language inspired by the language expressed in examples of the lolcat Internet meme. The language was created in 2007 by Adam Lindsay, researcher at the Computing Department of Lancaster University.
The language is not clearly defined in terms of operator priorities and correct syntax, but several functioning interpreters and compilers already exist. One interpretation of the language has been proven Turing-complete.
Language structure and examples
LOLCODE’s keywords are drawn from the heavily compressed (shortened) patois of the lolcat Internet meme. Here follows a Hello world program and a simple program to output a file to a monitor. Similar code was printed in the Houston Chronicle.
Example 1
HAI CAN HAS STDIO? VISIBLE "HAI WORLD!" KTHXBYE
HAI: In all LOLCODE programs, HAI (“Hi!”) introduces the program.
CAN HAS [LIBRARY]? : In many programming languages, one of the first statements will be a library inclusion for common functions such as input and output. Typically this is included by a call such as #include <stdio.h> [stdio standing for standard input/output library]. This command is a tongue-in-cheek corruption of that, asking if a library is obtainable, obtaining it if possible, and raising an exception if not. It is there primarily for authenticity — in fact, it is ignored in current implementations of LOLCODE.
VISIBLE [MESSAGE]: prints a message to the screen.
KTHXBYE: Just as HAI introduces the program, KTHXBYE (meaning “Okay thanks, bye”) terminates it.
Example 2
HAI CAN HAS STDIO? PLZ OPEN FILE "LOLCATS.TXT"? AWSUM THX VISIBLE FILE O NOES INVISIBLE "ERROR!" KTHXBYE
In this example, commands to open a file (PLZ OPEN FILE “NAME”? — “Please try to open a file?”), and error handling (AWSUM THX — “Awesome, thanks!”, and O NOES — “Oh no!”) are introduced.
Other commands include I HAS A variable for declaring variables, variable R value (“variable [is/are/being] value”) for assigning them, sending error messages to the front end via INVISIBLE instead of VISIBLE, and BTW (“by the way”) to denote a comment, making the parser ignore the rest of the line. Loops are created with IM IN YR label (from an internet meme “I’m in your ___”), and ended with IM OUTTA YR label. Loops lack counters or conditions, and thus do not cease inherently. They must be manually broken with the ENUF, “enough” in Leetspeak (old version GTFO) command. Loops can also be ended with the conditional IZ command:
HAI CAN HAS STDIO? I HAS A VAR IM IN YR LOOP UP VAR!!1 VISIBLE VAR IZ VAR BIGGER THAN 10? KTHX IM OUTTA YR LOOP KTHXBYE
This simple program displays the numbers 1–10 and terminates (as of specification 1.0). The same program as of specification 1.2 is (assuming VAR starts at 0):
HAI CAN HAS STDIO? IM IN YR LOOP UPPIN YR VAR TIL BOTH SAEM VAR AN 10 VISIBLE SUM OF VAR AN 1 IM OUTTA YR LOOP KTHXBYE
Implementations
The first LOLCODE implementation was a PHP parser written by Jeff Jones. The parser’s website was also the first website using LOLCODE as an actual web scripting language. Being open source with a BSD style license, it has been forked and used by multiple websites to implement LOLCODE scripting. The winning Pecha Kucha presentation at PHP Works 2008 was about this parser.
There is a .NET compiler for LOLCODE written by Nick Johnson, and featured in Microsoft developer training seminars, TechEd 2007 Conference (Australia).
PL/LOLCODE, a project headed by Josh Tolley, makes LOLCODE available as a server-side programming language inside PostgreSQL.
MicrosoftDynamic Language Runtime has an implementation of LOLCODE for testing purposes.
A LOLCODE to JavaScript translator is also available
There is also a LOLCODE compiler included with the Parrot virtual machine as one of the languages demonstrating the use of Parrot’s compiler tools.
A low-level interpreter written in C exists, maintained by Justin J. Meza, to provide native LOLCODE interpretation on a variety of platforms.
Related projects
LOLCODE has also inspired LOLPython, written by Andrew Dalke. LOLPython uses LOL-inspired syntax similar to that of LOLCODE, but with a Python-like style. It operates by translating the LOLPython source into Python code.
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