177 lines
7.1 KiB
HTML
177 lines
7.1 KiB
HTML
<!doctype html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Thun</title>
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<link rel="stylesheet" href="/css/site.css">
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</head>
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<body>
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<h1>Thun</h1>
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<p>A Dialect of Joy.</p>
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<p>version 0.5.0</p>
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<blockquote>
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<p>Simple pleasures are the best.</p>
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</blockquote>
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<p>Joy is a programming language created by Manfred von Thun that is easy to
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use and understand and has many other nice properties. This project
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implements interpreters for a dialect that attempts to stay very close to
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the spirit of Joy but does not precisely match the behaviour of the
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original version written in C.</p>
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<p>Joy is:</p>
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<ul>
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<li><a href="https://en.wikipedia.org/wiki/Purely_functional_programming">Purely Functional</a></li>
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<li><a href="https://en.wikipedia.org/wiki/Stack-oriented_programming_language">Stack-based</a></li>
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<li><a href="https://en.wikipedia.org/wiki/Concatenative_programming_language">Concatinative</a> (See also <a href="http://www.concatenative.org/wiki/view/Concatenative%20language">concatenative.org</a>)</li>
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<li><a href="https://joypy.osdn.io/notebooks/Categorical.html">Categorical</a></li>
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</ul>
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<p>The best source (no pun intended) for learning about Joy is the
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information made available at the
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<a href="http://www.latrobe.edu.au/humanities/research/research-projects/past-projects/joy-programming-language">website of La Trobe University</a>
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which contains source code for the original C interpreter, Joy language source code for various functions,
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and a great deal of fascinating material mostly written by Von Thun on
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Joy and its deeper facets as well as how to program in it and several
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interesting aspects. It's quite a treasure trove.</p>
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<h2>Example Code</h2>
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<p>Here is an example of Joy code:</p>
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<pre><code>[ [[abs] ii <=]
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[
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[<>] [pop !-] ||
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] &&
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]
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[[ !-] [[++]] [[--]] ifte dip]
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[[pop !-] [--] [++] ifte ]
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ifte
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</code></pre>
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<p>It might seem unreadable but with a little familiarity it becomes just as legible as any other notation.</p>
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<p>This function accepts two integers on the stack and increments or
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decrements one of them such that the new pair of numbers is the next
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coordinate pair in a square spiral (like the kind used to construct an
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<a href="https://en.wikipedia.org/wiki/Ulam_spiral">Ulam Spiral</a>
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). For more information see <a href="/notebooks/Square_Spiral.html">Square Spiral Example Joy Code</a></p>
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<h2>Project Hosted on <a href="https://osdn.net/projects/joypy/">OSDN</a></h2>
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<ul>
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<li><a href="https://osdn.net/projects/joypy/scm/git/Thun/">Source Repository</a> (<a href="https://github.com/calroc/Thun">mirror</a>)</li>
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<li><a href="https://todo.sr.ht/~sforman/thun-der">Bug tracker</a> (<a href="https://osdn.net/projects/joypy/ticket/">old tracker</a>)</li>
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<li><a href="https://osdn.net/projects/joypy/forums/">Forums</a></li>
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<li><a href="https://osdn.net/projects/joypy/lists/">Mailing list</a></li>
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</ul>
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<h2>Directory structure</h2>
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<pre><code>Thun
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|-- LICENSE - GPLv3
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|-- README.md - this file
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|-- archive
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| |-- Joy-Programming.zip
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| `-- README
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|-- docs
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| |-- Makefile - Generate https://joypy.osdn.io/ site.
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| |-- notebooks - Jupyter Notebooks and supporting modules
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| |-- reference - Docs for each function.
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| |-- dep-graphs - Generated dependency graphs.
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| `-- README - Table of Contents
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`-- implementations
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|-- Nim - interpreter
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|-- Prolog - interpreter
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| type inference
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| work-in-progress compiler
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|-- Python - interpreter
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`-- defs.txt - common Joy definitions for all interpreters
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</code></pre>
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<h2>Documentation</h2>
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<h3>Jupyter Notebooks</h3>
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<p>The docs/notebooks dir contains Jupyter notebooks, ... TODO</p>
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<h3>Building the Docs</h3>
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<p>Run <code>make</code> in the <code>docs</code> directory.</p>
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<h2>Basics of Joy</h2>
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<p>Joy is stack-based. There is a main stack that holds data items:
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integers, floats, strings, functions, and sequences or quotes which hold
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data items themselves.</p>
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<pre><code>23 1.8 'a string' "another" dup [21 18 /] [1 [2 [3]]]
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</code></pre>
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<p>A Joy expression is just a sequence (a.k.a. "list") of items. Sequences
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intended as programs are called "quoted programs". Evaluation proceeds
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by iterating through the terms in the expression, putting all literals
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onto the main stack and executing functions as they are encountered.
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Functions receive the current stack and return the next stack.</p>
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<h3>Literals and Simple Functions</h3>
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<pre><code>joy? 1 2 3
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. 1 2 3
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1 . 2 3
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1 2 . 3
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1 2 3 .
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1 2 3 <-top
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joy? + +
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1 2 3 . + +
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1 5 . +
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6 .
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6 <-top
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joy? 7 *
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6 . 7 *
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6 7 . *
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42 .
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42 <-top
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joy?
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</code></pre>
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<h3>Combinators</h3>
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<p>The main loop is very simple as most of the action happens through what
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are called "combinators": functions which accept quoted programs on the
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stack and run them in various ways. These combinators factor specific
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patterns that provide the effect of control-flow in other languages (such
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as ifte which is like if..then..else..) Combinators receive the current
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expession in addition to the stack and return the next expression. They
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work by changing the pending expression the interpreter is about to
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execute. The combinators could work by making recursive calls to the
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interpreter and all intermediate state would be held in the call stack of
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the implementation language, in this joy implementation they work instead
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by changing the pending expression and intermediate state is put there.</p>
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<pre><code>joy? 23 [0 >] [dup --] while
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...
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-> 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
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</code></pre>
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<h2>TODO:</h2>
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<p>§.4.4 Definitions and More Elaborate Functions</p>
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<p>§.4.5 Programming and Metaprogramming</p>
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<p>§.4.6 Refactoring</p>
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<p>§.6 References & Further Reading</p>
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<p><a href="https://en.wikipedia.org/wiki/Joy_%28programming_language%29">Wikipedia entry for Joy</a></p>
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<p><a href="http://www.latrobe.edu.au/humanities/research/research-projects/past-projects/joy-programming-language">Homepage at La Trobe University</a></p>
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<hr>
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<p>Misc...</p>
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<p>Stack based - literals (as functions) - functions - combinators -
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Refactoring and making new definitions - traces and comparing
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performance - metaprogramming as programming, even the lowly integer
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range function can be expressed in two phases: building a specialized
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program and then executing it with a combinator - ?Partial evaluation?
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- ?memoized dynamic dependency graphs? - algebra</p>
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<hr>
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<p>Copyright © 2014-2022 Simon Forman</p>
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<p>This file is part of Thun</p>
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<p>Thun is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any
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later version.</p>
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<p>Thun is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.</p>
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<p>You should have received a copy of the GNU General Public License along
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with Thun. If not see <a href="http://www.gnu.org/licenses/">http://www.gnu.org/licenses/</a>.</p>
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</body>
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