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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 %} + |