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Version 0.4. Everything subject to change.

yoob.js is the HTML5 counterpart to yoob.

Like yoob, yoob.js:

  • provides a set of components for implementing visual interpreters for esoteric programming languages (esolangs).
  • is written amateurishly.
  • has an API that is not particularly good, finalized, or stable.
  • will eventually ship with some public-domain implementations of some esolangs (but the approach is different from yoob's; see below.)

Unlike yoob, yoob.js:

  • is written in Javascript which assumes HTML5 capabilities in the browser (mainly <canvas> elements.)
  • does not provide a single canonical overarching framework which "knows" how to interpret and display and run an esolang implementation. Instead, more fitting with the dynamic approach of the Javascript language, yoob.js provides the constituent parts, and it's up to the developer to string them together into an esolang interpreter (or whatever else) and to lay it out on a web page.
  • is not limited to providing support for esolang interpreters; it might be better described as a set of components for implementing esolangs "and other bizarre things".
  • does not support unbounded integer values (yet; see "Planned", below).
  • provides components which are meant to be used as starting points for further modification. (It's all public domain, so build on it!) For example, yoob.SexpParser is meant to be used as an example or basis for a specific grammar of your choice.

yoob.js will eventually:

  • extend the idea of "a component to help implement an esolang" to encompass esolang implementations themselves. So, for example, yoob.js might include an implementation of brainfuck, but this would not be provided solely as an "end implementation" but also as a component for implementing other brainfuck-derived esolangs, and other mashups.

    This emphasizes a thing with yoob, which is that while the yoob distribution may contain implementations of various languages, it does not contain the reference implementation of any language; but the reference implementations of some languages may be written in yoob. yoob allows for this approach, but yoob.js hopes to accomodate it better than just allowing for it.

Other things you should know about yoob.js are that it:

  • requires features from HTML5 and related "modern" web standards. It does not try to do any feature detection or polyfilling. If it doesn't work in your browser, it doesn't work in your browser. Try another browser.
  • does not rely on jQuery (yet) (possibly to its detriment.)
  • does not come minified or agglomerated or anything. I mean, this isn't production web development, we're not trying to optimize page load time here, we just want to run us some esolangs, right? You're free to do this yourself. May we suggest cat yoob/*.js > yoob.js? (Note: there may one day be a small script to do this sort of thing for you, more intelligently, respecting dependencies and whatnot. Especially if you write it and send a pull request.)


Each yoob.js class is defined in its own .js file, and each .js file inserts the class it defines into the yoob namespace (which it will create as a new, empty, global namespace if it has not already been defined.)

The classes are currently:

  • yoob.Playfield, in yoob/playfield.js

    A two-dimensional Cartesian grid of values which dynamically expands as needed. Objects of this class are suitable for representing programs in two-dimensional esolangs such as Befunge, as well as cellular automata, and suitable for use as a backing store for a text-terminal simulator.

  • yoob.Cursor, in yoob/cursor.js

    A pointer (position vector) into two-dimensional Cartesian space (typically a yoob.Playfield) which also has a delta (direction vector) which need not necessarily be used.

  • yoob.PlayfieldCanvasView, in yoob/playfield-canvas-view.js

    A view (in the MVC sense) which associates a yoob.Playfield with a <canvas> element in the DOM. The playfield will be depicted on the canvas, which can also dynamically expand as needed.

  • yoob.PlayfieldHTMLView, in yoob/playfield-html-view.js

    A view (in the MVC sense) which associates a yoob.Playfield with any element which supports innerHTML, although typically a <pre> element. Compared to the canvas view, this view will allow text to be rendered more nicely in some browsers, be selected for copying/pasting in the browser, and so forth. As of 0.4, this is not yet complete.

  • yoob.TextTerminal, in yoob/text-terminal.js

    A crude simulation of a text-based addressable console, including some functions (which need not be used) which understand simple terminal control sequences, such as LF and backspace. Requires yoob.Playfield and yoob.Cursor and, if you actually want to render the terminal in a browser DOM, yoob.PlayfieldCanvasView or a compatible playfield view class.

  • yoob.LineInputBuffer, in yoob/line-input-buffer.js

    A crude simulation of a buffer into which the user can type a line of text. Typically it is associated with a yoob.TextTerminal object, on which the text is displayed as the user types it.

  • yoob.Tape, in yoob/tape.js

    A (theoretically) unbounded tape, like you'd find on a Turing machine, optionally associated with a <canvas> on which it is depicted.

  • yoob.TapeHead, in yoob/tape-head.js

    An object representing a position on a Tape.

  • yoob.Stack, in yoob/stack.js

    An object implementing a push-down, first-in-first-out stack of values, optionally associated with a <canvas> on which it is depicted.

  • yoob.Tree, in yoob/tree.js

    A multi-purpose, n-ary tree, with optional node name (String identifier) and payload (arbitrary value.) Children are indexed by integer, 0-based. It's meant to serve two main purposes:

    • as an AST (Abstract Syntax Tree) for the (initial) intermediate representation(s) of a program in an interpreter or compiler, in which case the node name is the node type and the payload is anything that might be handy, such as what the tree evaluated to; and
    • as terms, roughly as defined in the science of term rewriting. In this case the node name is the "constructor" and the payload is probably not used. For this purpose, the tree.js module should eventually include facilities for matching and unification.

    Trees, with only two children, could also be used as lists a la Lisp. In this case the node name and payload would both go unused.

  • yoob.Scanner, in yoob/scanner.js

    A simple, inefficient lexical analyzer, parameterized with a table of regexps. Can also serve as a starting point for writing your own, less simple, inefficient lexical analyzer.

  • yoob.SexpParser, in yoob/sexp-parser.js

    A simple recursive-descent parser which parses S-expressions. Uses yoob.Scanner to analyze the input string and yoob.AST to create the parsed version. Can also serve as a starting point for writing your own recursive-descent parser for some other, more complex language.

  • yoob.Controller, in yoob/controller.js

    A controller for animating the evolution and animation of a state (such as an esolang program state or a cellular automaton configuration). Can be hooked up to DOM elements in the UI (typically buttons.)

  • yoob.Sprite and yoob.SpriteManager, in yoob/sprite-manager.js

    A set of classes for (somewhat crudely) managing independent things which can be placed, moved, be clicked, and be dragged around a canvas.


  • yoob.Environment

    A scoped associative structure, suitable for implementing a symbol table or an evaluation context.

  • yoob.Turtle

    For Turtle Graphics. This should probably be a "model" and there should be a separate yoob.TurtleView which concerns itself with rendering the turtle (and its path) on a canvas.

  • yoob.Error

    For error handling. Scanning and Parsing should accumulate a list of these objects before choking and dying. They should be displayable nicely somehow.

  • unbounded integer support

    Although yoob.js will likely not ship with an unbounded integer implementation (unless someone wants to contribute one), certain classes (Tape, Stack, Playfield) should probably, one day, have limited support for working with objects which conform to a subset of the API exposed by Matthew Crumley's Javascript BigInteger class, which is unastonishing.

Used in

yoob.js is currently used in the HTML5 implementations of:

...and soon to be used in ALPACA and the various cellular automata defined therein.


  • version 0.1

    Initial release.

  • version 0.2

    Added yoob.Controller class.

    In yoob.Playfield: made attributes camelCase added support for transformer argument to load added support for default values (setDefault) added dump method added putDirty and recalculateBounds methods added map method

  • version 0.3

    Added embed-sources tool.

    Added yoob.SpriteManager and yoob.Sprite classes.

    Moved yoob.AST to yoob.Tree, and added equals, setValue, setVariable, match, and subst methods to it.

    Added support for edit and select controls in yoob.Controller.

    Added get(Max|Min)(X|Y) methods to yoob.Playfield, and fixed issue with drawing cursors at wrong offsets.

  • version 0.4

    Moved all-display related code from yoob.Playfield into a new class, yoob.PlayfieldConsoleView; in MVC parlance, yoob.Playfield is now a "model", and to actually display it in a browser, you will need a "view".

    yoob.PlayfieldConsoleView has a drawCell method instead of the old drawElement which will try to call draw on the value in the cell, if it has such a method, and will also takes (and will pass) the x and y co-ordinates of the cell in the playfield being drawn.

    Removed yoob.TextConsole; use yoob.TextTerminal and don't call write(), just call writeRaw(), if you want a console that doesn't understand terminal control codes.

    Refactored yoob.TextTerminal to be a facade over a yoob.Playfield and a yoob.Cursor. Thus, you can now read characters from any position in the terminal — however it has lost the ability to overstrike characters. Again, since yoob.Playfield is now a "model", yoob.TextTerminal itself does not concern itself with displaying the terminal (although there is a helper method to create a canvas view.)

    yoob.LineInputBuffer generally improved; it listens to keydown instead of keyup for special keys, prevents the default action for them, and has been tested in Firefox, Chrome, and Internet Explorer (recent versions.)