|Designed by||Adam Lindsay|
|Filename extensions||.lol, .lols|
LOLCODE is an esoteric programming language inspired by lolspeak, 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 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 follow a "Hello, World!" program and a simple program to output a file to a monitor. Similar code was printed in the Houston Chronicle.
HAI 1.2 CAN HAS STDIO? VISIBLE "HAI WORLD!" KTHXBYE
In all LOLCODE programs, HAI ("Hi!") introduces the program and specifies the version (although this isn't actually used yet).
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 verisimilitude—in fact, it is ignored in current implementations of LOLCODE.
Prints a message to the screen.
HAIintroduces the program,
KTHXBYE(which is "K," "THX," and "Bye" all strung together, meaning "OK, thanks, bye") terminates it.
To write a single line comment in LOLCODE, you use the
BTWkeyword. Comments are ignored by the compiler and are written for better understanding of the program.
Similar to the
OBTWkeyword marks a multiline comment, a comment that spans multiple lines. In LOLCODE, the
OBTWkeyword signifies the start of a multiline comment while the
TLDRkeyword ends it.
HAI 1.2 CAN HAS STDIO? PLZ OPEN FILE "LOLCATS.TXT"? AWSUM THX VISIBLE FILE O NOES INVISIBLE "ERROR!" KTHXBYE
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
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'' (inspired by the "Im in ur noun, verbing yr related noun" LOLcat meme), and ended with
IM OUTTA YR ''label''. Loops can be broken with the keyword
ENUF ("enough"), or in older versions,
GTFO. Loops can also be ended with the conditional
IZ command, as demonstrated in the next example.
HAI 1.0 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 1–11 and terminates (as of specification 1.0). The same program as of specification 1.2 is (assuming VAR starts at 0):
HAI 1.2 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
HAI 1.0 CAN HAS STDIO? VISIBLE "U SEE THIS" BTW VISIBLE "U SEE NOTHING" OBTW VISIBLE "U SEE NOTHIN" VISIBLE "U STIL SEE NOTHIN" TLDR VISIBLE "U SEE THIS" KTHXBYE
The above example will return the following:
U SEE THIS U SEE THIS
This is because line 3 outputs
U SEE THIS but line 5 is ignored due to the fact that it is commented out by the
BTW keyword. Lines 8 and 9 aren't run because they are in a multiline comment that starts in line 7, and ends on line 10. Line 12 outputs
U SEE THIS and line 13 terminates the program.
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 licence, 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.
PL/LOLCODE, a project headed by Josh Tolley, makes LOLCODE available as a server-side programming language inside PostgreSQL.
lolcode-java (A Java grammar / interpreter for the LOLCODE programming language) is a project also available but it appears to not yet be compliant with the version 1.3 specification.
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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