Base template tweaked, old Grasp/Thue articles added from previous website efforts

author: Jed Barber <jjbarber@y7mail.com> 2017-01-01 15:00:53 +1100
committer: Jed Barber <jjbarber@y7mail.com> 2017-01-01 15:00:53 +1100
commit: 4e7fdd57cbf8f60f674ba48fd04c80ad59a20579 (patch)
tree: 93d4ba886963ba10a8fbf9f24888696a6b8fd15c /project/templates
parent: 3daacbded8cac1cad5bab6a593e5f021e4e01ca7 (diff)
4 files changed, 177 insertions, 4 deletions
diff --git a/project/templates/base.html b/project/templates/base.html
index 2e5a549..7a215a4 100644
--- a/project/templates/base.html
+++ b/project/templates/base.html
@@ -2,14 +2,16 @@
 <html lang="en">
 <head>
     <meta charset="utf-8">
-    <title>Jed Barber - {% block title %}{% endblock %}</title>
+    <title>{% block title %}{% endblock %}</title>
     <link href="/css/default.css" rel="stylesheet">
 </head>
 <body>
+    <h2>Jedidiah Barber's Personal Site</h2>
+    <hr>
     <nav>
         <ul>
             <li><a href="/">Index</a></li>
-            <!--<li><a href="/about.html">About</a></li>-->
+            <li><a href="/about.html">About</a></li>
             <li><a href="/git.html">Git</a></li>
         </ul>
     </nav>
@@ -20,3 +22,4 @@
     </article>
 </body>
 </html>
+
diff --git a/project/templates/grasp.html b/project/templates/grasp.html
new file mode 100644
index 0000000..e591d92
--- /dev/null
+++ b/project/templates/grasp.html
@@ -0,0 +1,70 @@
+
+{% extends "base.html" %}
+
+
+
+{% block title %}Grasp Interpreter{% endblock %}
+
+
+
+{% block content %}
+
+<h4>Grasp Interpreter</h4>
+
+<p>Like Lisp, the esoteric programming language <a href="http://esolangs.org/wiki/Grasp">Grasp</a>
+is a homoiconic language that exclusively uses a single datatype. Except instead of lists, it uses
+directed graphs.</p>
+
+<p>A Grasp program is initialised with instruction pointers to those nodes in the graph that have
+a "name" edge to a node with the value "grasp:main". The nodes at each instruction pointer are
+evaluated and the pointer then updated by following an available "next" edge. This continues until
+all instruction pointers have no more "next" edges to follow.</p>
+
+<figure>
+    <img src="/img/grasp_helloworld.png"
+         alt="Hello World in Grasp"
+         height="176"
+         width="268">
+    <figcaption>Hello World in Grasp</figcaption>
+</figure>
+
+<p>In the <a href="https://github.com/fis/grajsp/wiki/Grasp-specification">current specification</a>,
+the actions that can be performed are:</p>
+
+<ul>
+    <li>add or delete an edge</li>
+    <li>change the value of a node</li>
+    <li>add, subtract, multiply, divide, or modulo node values</li>
+    <li>call and return from functions, which take the form of subgraphs with named entry points</li>
+    <li>read and write from arbitrary file handles</li>
+    <li>push, pop and pick a section of nodes arranged to act as a stack</li>
+</ul>
+
+<p>The execution of a node may be skipped by having "cond" edges pointing to either zero values or
+non-numeric values. Also, due to the way instruction pointers update and the way several instructions
+are defined, there is a measure of non-determinism that can be introduced depending on what
+edges are available.</p>
+
+<p>The language seemed like an interesting enough idea, but unfortunately nobody had done anything
+with it, and there was only a specification. This has now been fixed. The interpreter currently
+uses a subset of the DOT graph description language for the file format, to enable a text format
+as well as relatively easy conversion to a graph image. If a format that more readily converts to a
+comprehensible graph image is found, a parser for it may be added.</p>
+
+<p>The above example is recorded as follows:
+<code>
+    digraph {
+        1 [label="puts"]
+        2 [label="grasp:main"]
+        3 [label="Hello world!"]
+    
+        1 -> 2 [label="name"]
+        1 -> 3 [label="in"]
+    }
+</code>
+</p>
+
+<p>Source code is available <a href="https://github.com/jedb/esoteric">here</a>.</p>
+
+{% endblock %}
+
diff --git a/project/templates/index.html b/project/templates/index.html
index 14b9c97..70aafcb 100644
--- a/project/templates/index.html
+++ b/project/templates/index.html
@@ -1,8 +1,11 @@
 
 {% extends "base.html" %}
 
-{% block title %}Index{% endblock %}
+{% block title %}Jedidiah Barber's Personal Site{% endblock %}
 
 {% block content %}
-    <p>Content for index goes here</p>
+    <ul class="index">
+        <li><a href="/grasp.html">Grasp Interpreter</a></li>
+        <li><a href="/thue2a.html">Thue Version 2a</a></li>
+    </ul>
 {% endblock %}
diff --git a/project/templates/thue2a.html b/project/templates/thue2a.html
new file mode 100644
index 0000000..c0430db
--- /dev/null
+++ b/project/templates/thue2a.html
@@ -0,0 +1,97 @@
+
+{% extends "base.html" %}
+
+
+
+{% block title %}Thue Version 2a{% endblock %}
+
+
+
+{% block content %}
+
+<h4>Thue Version 2a</h4>
+
+<p><a href="http://esolangs.org/wiki/Thue">Thue</a> is an esoteric programming language
+based on unrestricted grammars. A Thue program consists of a number of rules detailing a
+sequence of symbols to replace and a sequence of symbols to replace with, and an initial
+state of the program. Applicable rules are then applied to the inital state in a random
+order until no more are applicable, at which point the program terminates.</p>
+
+<p>An example Thue program that increments a binary number surrounded by '_' characters:
+<code>
+    1_::=1++
+    0_::=1
+    01++::=10
+    11++::=1++0
+    _0::=_
+    _1++::=10
+    ::=
+    _1111111_
+</code>
+</p>
+
+<p>The before and after symbols in each rule are separated by '::=' and the list of rules is
+ended by a blank rule. Note that whitespace in rules and the inital state is NOT ignored.</p>
+
+<p>Output is handled by prefixing the right hand side with '~', which causes those symbols to
+go to stdout and the replacement in the program to be the empty string.</p>
+
+<p>The traditional Hello World program:
+<code>
+    a::=~Hello World!
+    ::=
+    a
+</code>
+</p>
+
+<p>Input is handled by having the right hand side of a rule be ':::', which causes the left
+hand side symbols to be replaced with a line from the standard output. Unfortunately, this
+immediately causes problems.</p>
+
+<p>The following is an innocent piece of code that accepts a single line of input and does nothing
+more. Maybe.
+<code>
+    a::=:::
+    ::=
+    a
+</code>
+</p>
+
+<p>If a string involving the letter 'a' is entered into the above program, the single input rule
+will again become applicable and another line of input will be obtained. In other words, the
+input in Thue is unescaped and allows direct code injection into a program.</p>
+
+<p>To solve this problem, I've constructed a slightly modified version of Thue that I'm calling
+version 2a. In this version, all symbols obtained through stdin are treated as different from
+ordinary symbols. Rules can refer to and manipulate symbols obtained through stdin by
+surrounding them in double quotes.</p>
+
+<p>A rule that replaces an ordinary symbol 'a' with 'abc':
+<code>
+    a::=abc
+</code>
+</p>
+
+<p>A rule that replaces the letter 'a' that was obtained from stdin with 'abc':
+<code>
+    "a"::=abc
+</code>
+</p>
+
+<p>For convenience, a number of escaped characters are also available:
+<pre>
+    \\ -> backslash
+    \r -> return
+    \n -> newline
+    \: -> colon
+    \" -> double quote
+    \EOT -> end of file
+</pre>
+</p>
+
+<p>While this doesn't solve all the problems Thue has (try writing a Thue program that asks
+for and greets the user by name!) it should solve this one particular issue. Source code is
+available <a href="https://github.com/jedb/esoteric">here</a>.</p>
+
+{% endblock %}
+
author	Jed Barber <jjbarber@y7mail.com>	2017-01-01 15:00:53 +1100
committer	Jed Barber <jjbarber@y7mail.com>	2017-01-01 15:00:53 +1100
commit	4e7fdd57cbf8f60f674ba48fd04c80ad59a20579 (patch)
tree	93d4ba886963ba10a8fbf9f24888696a6b8fd15c /project/templates
parent	3daacbded8cac1cad5bab6a593e5f021e4e01ca7 (diff)