mirror of
https://github.com/ganelson/inform.git
synced 2024-07-18 06:54:26 +03:00
153 lines
10 KiB
HTML
153 lines
10 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<head>
|
|
<title>What This Module Does</title>
|
|
<link href="../docs-assets/Breadcrumbs.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<meta name="viewport" content="width=device-width initial-scale=1">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<meta http-equiv="Content-Language" content="en-gb">
|
|
|
|
<link href="../docs-assets/Contents.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<link href="../docs-assets/Progress.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<link href="../docs-assets/Navigation.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<link href="../docs-assets/Fonts.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<link href="../docs-assets/Base.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<script src="http://code.jquery.com/jquery-1.12.4.min.js"
|
|
integrity="sha256-ZosEbRLbNQzLpnKIkEdrPv7lOy9C27hHQ+Xp8a4MxAQ=" crossorigin="anonymous"></script>
|
|
|
|
<script src="../docs-assets/Bigfoot.js"></script>
|
|
<link href="../docs-assets/Bigfoot.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
<link href="../docs-assets/Colours.css" rel="stylesheet" rev="stylesheet" type="text/css">
|
|
|
|
</head>
|
|
<body class="commentary-font">
|
|
<nav role="navigation">
|
|
<h1><a href="../index.html">
|
|
<img src="../docs-assets/Inform.png" height=72">
|
|
</a></h1>
|
|
<ul><li><a href="../index.html">home</a></li>
|
|
</ul><h2>Compiler</h2><ul>
|
|
<li><a href="../structure.html">structure</a></li>
|
|
<li><a href="../inbuildn.html">inbuild</a></li>
|
|
<li><a href="../inform7n.html">inform7</a></li>
|
|
<li><a href="../intern.html">inter</a></li>
|
|
<li><a href="../services.html">services</a></li>
|
|
</ul><h2>Other Tools</h2><ul>
|
|
<li><a href="../inblorbn.html">inblorb</a></li>
|
|
<li><a href="../indocn.html">indoc</a></li>
|
|
<li><a href="../inform6.html">inform6</a></li>
|
|
<li><a href="../inpolicyn.html">inpolicy</a></li>
|
|
<li><a href="../inrtpsn.html">inrtps</a></li>
|
|
</ul><h2>Resources</h2><ul>
|
|
<li><a href="../extensions.html">extensions</a></li>
|
|
<li><a href="../kits.html">kits</a></li>
|
|
</ul><h2>Repository</h2><ul>
|
|
<li><a href="https://github.com/ganelson/inform"><img src="../docs-assets/github.png" height=18> github</a></li>
|
|
</ul><h2>Related Projects</h2><ul>
|
|
<li><a href="../../../inweb/docs/index.html">inweb</a></li>
|
|
<li><a href="../../../intest/docs/index.html">intest</a></li>
|
|
|
|
</ul>
|
|
</nav>
|
|
<main role="main">
|
|
<!--Weave of 'What This Module Does' generated by Inweb-->
|
|
<div class="breadcrumbs">
|
|
<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../inform7n.html">Inform7</a></li><li><a href="index.html">knowledge</a></li><li><a href="index.html#P">Preliminaries</a></li><li><b>What This Module Does</b></li></ul></div>
|
|
<p class="purpose">An overview of the knowledge module's role and abilities.</p>
|
|
|
|
<ul class="toc"><li><a href="P-wtmd.html#SP1">§1. Prerequisites</a></li><li><a href="P-wtmd.html#SP2">§2. The Model</a></li></ul><hr class="tocbar">
|
|
|
|
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>§1. Prerequisites. </b>The knowledge module is a part of the Inform compiler toolset. It is
|
|
presented as a literate program or "web". Before diving in:
|
|
</p>
|
|
|
|
<ul class="items"><li>(a) It helps to have some experience of reading webs: see <a href="../../../inweb/docs/index.html" class="internal">inweb</a> for more.
|
|
</li><li>(b) The module is written in C, in fact ANSI C99, but this is disguised by the
|
|
fact that it uses some extension syntaxes provided by the <a href="../../../inweb/docs/index.html" class="internal">inweb</a> literate
|
|
programming tool, making it a dialect of C called InC. See <a href="../../../inweb/docs/index.html" class="internal">inweb</a> for
|
|
full details, but essentially: it's C without predeclarations or header files,
|
|
and where functions have names like <span class="extract"><span class="extract-syntax">Tags::add_by_name</span></span> rather than just <span class="extract"><span class="extract-syntax">add_by_name</span></span>.
|
|
</li><li>(c) This module uses other modules drawn from the compiler (see <a href="../structure.html" class="internal">structure</a>), and also
|
|
uses a module of utility functions called <a href="../../../inweb/docs/foundation-module/index.html" class="internal">foundation</a>.
|
|
For more, see <a href="../../../inweb/docs/foundation-module/P-abgtf.html" class="internal">A Brief Guide to Foundation (in foundation)</a>.
|
|
</li></ul>
|
|
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>§2. The Model. </b>This module's task is to build the "model world", the initial state of the
|
|
world as it is chosen by an Inform author.<sup id="fnref:1"><a href="#fn:1" rel="footnote">1</a></sup> This consists of:
|
|
</p>
|
|
|
|
<ul class="items"><li>● Kinds, such as "vehicle", created in source text.
|
|
</li><li>● Instances of kinds, such as a specific lorry in a fictional world being
|
|
created with Inform.
|
|
</li><li>● Permanently existing variables, which have kinds and initial values.
|
|
</li><li>● Either-or properties, which individual instances might or might not have:
|
|
for example, the lorry might be "parked" or "not parked".
|
|
</li><li>● Properties with values, which some instances will have and some will not,
|
|
and with differing values: for example, the colour of the lorry might be "yellow".
|
|
</li><li>● Relationships between instances. For example, a specific person might
|
|
"know how to drive" the yellow lorry, or might not.
|
|
</li></ul>
|
|
<p class="commentary">But the model does not contain:
|
|
</p>
|
|
|
|
<ul class="items"><li>● Kinds, such as "number", built in to Inform.<sup id="fnref:2"><a href="#fn:2" rel="footnote">2</a></sup>
|
|
</li><li>● Values, such as the number 176, which exist without anyone getting to
|
|
choose whether they should exist or not.
|
|
</li><li>● Temporary variables used during phrases or activities, but not existing
|
|
at the start of play.
|
|
</li><li>● Adjectives such as "even" as applied to numbers, or "empty" as applied
|
|
to containers, whose truth or falsity is determined by something other than
|
|
the author's whim. An author cannot choose that 176 is odd, and whether a
|
|
container is empty depends only on whether there is something in it.
|
|
</li><li>● Relationships which are, similarly, determined by an algorithm and not
|
|
by a specific authorial choice. Like it or not, 176 is "greater than" 8.
|
|
</li></ul>
|
|
<ul class="footnotetexts"><li class="footnote" id="fn:1"><p class="inwebfootnote"><sup id="fnref:1"><a href="#fn:1" rel="footnote">1</a></sup> The term "model" is drawn partly from interactive fiction, but also from
|
|
model theory in the sense of logic, where a "model" is a specific solution
|
|
showing that a set of logical propositions can all simultaneously be true.
|
|
<a href="#fnref:1" title="return to text"> ↩</a></p></li><li class="footnote" id="fn:2"><p class="inwebfootnote"><sup id="fnref:2"><a href="#fn:2" rel="footnote">2</a></sup> Properly speaking, kinds created by Neptune files inside kits rather than
|
|
being declared in source text.
|
|
<a href="#fnref:2" title="return to text"> ↩</a></p></li></ul>
|
|
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>§3. </b>The model is constructed entirely from a stream of logical propositions
|
|
sent here by the <a href="../assertions-module/index.html" class="internal">assertions</a> module. Those propositions may be mutually
|
|
inconsistent — either flatly contradictory or just impossible to reconcile.
|
|
</p>
|
|
|
|
<p class="commentary">The stream of supposed truthful statements comes to this module through calls
|
|
to either <a href="1-ap.html#SP2" class="internal">Assert::true</a> or <a href="1-ap.html#SP2" class="internal">Assert::true_about</a>. These reduce a
|
|
proposition to a set of facts concerning things in the model; as we have
|
|
seen, the model includes kinds, variables, instances and relations, and so
|
|
we need a unified type for "something you can know a fact about". That
|
|
type is called <a href="4-is.html#SP6" class="internal">inference_subject</a>. Each subject has its own list of known
|
|
facts: we call such a fact an <a href="5-inf.html#SP1" class="internal">inference</a> because it has (usually) been
|
|
inferred from a proposition.
|
|
</p>
|
|
|
|
<p class="commentary"><a href="3-prp.html" class="internal">Chapter 3: Properties</a> implements our system of properties: each different value
|
|
or either-or property is a <a href="3-prp.html#SP1" class="internal">property</a> object. There might be a puritan
|
|
case for abolishing this type in favour of regarding either-or properties
|
|
as special cases of <span class="extract"><span class="extract-syntax">unary_predicate</span></span> and value properties as special cases
|
|
of <span class="extract"><span class="extract-syntax">binary_predicate</span></span> (by identifying a predicate with its setting relation),
|
|
but I do not think this would clarify anything.
|
|
</p>
|
|
|
|
<p class="commentary"><a href="4-is.html" class="internal">Chapter 4: Subjects</a> gives a general API for dealing with <a href="4-is.html" class="internal">Inference Subjects</a>,
|
|
and then works systematically through the various categories of these.
|
|
Kinds and binary predicates already exist from other modules (see
|
|
<a href="../kinds-module/2-knd.html" class="internal">Chapter 2: Kinds (in kinds)</a> and <a href="../calculus-module/3-bpf.html" class="internal">Chapter 3: Binary Predicates (in calculus)</a>
|
|
respectively), but <a href="2-ins.html" class="internal">Instances</a> and <a href="2-nv.html" class="internal">Nonlocal Variables</a> are new.
|
|
</p>
|
|
|
|
<p class="commentary">Finally, <a href="5-inf.html" class="internal">Chapter 5: Modelling</a> deals with the actual inferences, and with how the
|
|
model world is constructed. The core of Inform does nothing very interesting
|
|
here, but plugins from the <a href="../if-module/index.html" class="internal">if</a> module add some domain-specific savvy.
|
|
</p>
|
|
|
|
<nav role="progress"><div class="progresscontainer">
|
|
<ul class="progressbar"><li class="progressprevoff">❮</li><li class="progresscurrentchapter">P</li><li class="progresscurrent">wtmd</li><li class="progresschapter"><a href="1-km.html">1</a></li><li class="progresschapter"><a href="2-ins.html">2</a></li><li class="progresschapter"><a href="3-prp.html">3</a></li><li class="progresschapter"><a href="4-is.html">4</a></li><li class="progresschapter"><a href="5-inf.html">5</a></li><li class="progressnext"><a href="1-km.html">❯</a></li></ul></div>
|
|
</nav><!--End of weave-->
|
|
|
|
</main>
|
|
</body>
|
|
</html>
|
|
|