Whitespace (programming language)

from Wikipedia, the free encyclopedia
Whitespace source code with syntax highlighting
  • Tab characters
  • Spaces

    • Whitespace is a relatively young esoteric programming language . In contrast to common programming languages, the commands and control instructions consist of defined sequences of spaces, tabs and line breaks (English Whitespaces ). Besides this obvious quirk, Whitespace uses the usual dual system only for data; the program code is represented in a three-digit system of digits (“l”, “t”, “u” or “s”, “t”, “l”).

    syntax

    The commands and control statements consist of defined sequences of spaces (l), horizontal tab characters (t) and line breaks (u).

    There is no syntax element for marking comments. Instead, comments, which themselves must not contain whitespaces, can be entered anywhere in the source code. The interpreter ignores all characters that have no meaning for it.

    Commands

    The commands can be roughly divided into five areas:

    character meaning
    l Stack access
    tl Arithmetic functions
    dd Heap memory access
    u Loops, jumps, conditions
    do Input / output of values

    A detailed description of the individual commands including expected parameters can be found on the website mentioned below.

    Data

    While the commands use a three-value system of digits, the data are represented in the dual system: In the first position from the left, a t stands for a negative number; a l for a positive. In the following, t stands for 1 and l for 0. The specification states that numbers can have any bit length, but the compiler and interpreter can set a sensible upper limit here. A date is terminated by a line break.

    language

    Whitespace is an imperative , stack-based programming language that provides programmers with a stack and heap.

    All operations work internally on integers of any bit length. However, it is possible to output a character that is identified by its ASCII code value (outchar).

    History and background

    Whitespace was developed by Edwin Brady and Chris Morris in late 2002 . Slashdot reported on this programming language on April 1, 2003. In mid-2003, with the completion of a whitespace interpreter in whitespace, the language left the nursery. Bjarne Stroustrup had already mentioned the idea in a draft for C ++ 2000 five years earlier . His basic idea was that mathematicians usually write a space instead of the mark . In C ++ 2000, you could assign the meaning of multiplication to this space.

    Whitespace shows a certain similarity to Python programs and make files, because there tab characters at the beginning of the line control the program flow. Most other programming languages ​​ignore whitespaces. For the human observer, however, they serve a useful structuring that can make the program code easier to read.

    According to the inventors, advantages are that mass printouts of source texts save ink and that spies who have stolen the code cannot decipher it. However, there are still problems if you want to re-enter the code after printing.

    Whitespace is particularly suitable for hiding program code in normal text, similar to steganography . An example of this can be found in a contribution to the International Obfuscated C Code Contest .

    Hello World

    The “ Hello, world! "-Program: 

     lllullltlltllluttlllltulllttlltltuttlllltlulllttlttlluttllllttulllttlttlluttllll
 tllulllttlttttuttlllltltullltlttlluttllllttlullltllllluttlllltttullltttltttuttll
 lltlllulllttlttttuttlllltlltullltttlltluttlllltltlulllttlttlluttlllltlttulllttll
 tlluttllllttllullltlllltuttllllttltulllttltuttlllltttlullltltluttllllttttullllut
 tllllluulllltulultttlulutlltlutullllltutlllululltuullltluuuu

    Development environments

    The editor Vim offers syntax highlighting for whitespace by default, which significantly simplifies programming. However, this runs counter to a design goal of the language of using as little ink as possible when printing. There is a mode for Emacs at the web links .

    The "Hello, world!" can be converted to proper whitespace using one of the following scripts: 

     #!/bin/sh
 sed "s/ //g;s|//.*||g;s/\\n//g" $1 | tr -d '\n' | sed "s/l/ /g;s/t/\t/g;s/u/\n/g"

 #!/bin/sh
 sed "s|//.*||g" < $1 | tr -d " \t\n" | tr ltu " \t\n"

    sed is a Unix tool for editing text.

    Whitespace assembler

    Since dealing with trinary coded machine commands is relatively laborious, an equivalent assembler dialect is often used: 

     // "Hello, world!" in den Speicher schreiben
 lllu          // push 0   // Speicherstelle 0
 llltlltlllu   // push 'H' // Zeichen 'H'
 ttl           // store    // in den Speicher
 llltu         // push 1   // ...
 lllttlltltu   // push 'e'
 ttl           // store
 llltlu        // push 2
 lllttlttllu   // push 'l'
 ttl           // store
[…]
 lllttllu      // push 12
 llltlllltu    // push '!'
 ttl           // store
 lllttltu      // push 13
 lllttltu      // push \r
 ttl           // store
 llltttlu      // push 14
 llltltlu      // push \n
 ttl           // store
 lllttttu      // push 15
 llllu         // push 0
 ttl           // store

 // Ausgabe-Schleife:
 llllu         // push 0
 ulllltu       // 1:          // /Schleife
    lul           // dup      // | --.
    ttt           // pop      // |   --- Spitze des Stacks untersuchen
    lul           // dup      // | --'
    utlltlu       // jz 2     // | ----> bei 0 sind wir fertig
    tull          // outchar  // | ----> Ausgabe
    llltu         // push 1   // | --._. Speicherstelle hochzaehlen
    tlll          // add      // | --'
 ululltu       // jmp 1       //  \naechster Durchlauf
 ullltlu       // 2:          //
 uuu           // halt        // ende

    literature

    • Oliver Lau: Hexenwerk - A plea for esoteric programming languages : In: c't , 22/2007, pp. 192–199.

    Web links

    Individual evidence

    1. ^ New Whitespace-Only Programming Language , Slashdot, April 1, 2003
    2. ^ Bjarne Stroustrup: Generalizing Overloading for C ++ 2000 . (PDF) 1998