83 lines
3.9 KiB
HTML
83 lines
3.9 KiB
HTML
<?xml version="1.0" encoding="utf-8"?>
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml"><head>
|
|
<title>.</title>
|
|
<style type="text/css">
|
|
|
|
* { color: #000; background: #fff; max-width: 700px; }
|
|
tt, pre { background: #dedede; color: #111; font-family: monospace;
|
|
white-space: pre; display: block; width: 100%; }
|
|
.indentedcode { margin-left: 2em; margin-right: 2em; }
|
|
.codeblock {
|
|
background: #dedede; color: #111; font-family: monospace;
|
|
box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
|
|
padding: 7px;
|
|
display: block;
|
|
}
|
|
|
|
.indentedlist { margin-left: 2em; color: #000; }
|
|
|
|
span { white-space: pre; }
|
|
.text { color: #000; white-space: pre; background: #dedede; }
|
|
.colon { color: #000; background: #dedede; }
|
|
.note { color: #000; background: #dedede; }
|
|
.str { color: #000; text-decoration: underline; background: #dedede; }
|
|
.num { color: #000; background: #dedede; font-weight: bold; font-style: italic; }
|
|
.fnum { color: #000; font-weight: bold; background: #dedede; }
|
|
.ptr { color: #000; font-weight: bold; background: #dedede; }
|
|
.fetch { color: #000; font-style: italic; background: #dedede; }
|
|
.store { color: #000; font-style: italic; background: #dedede; }
|
|
.char { color: #000; background: #dedede; }
|
|
.inst { color: #000; background: #dedede; }
|
|
.defer { color: #000; background: #dedede; }
|
|
.imm { color: #000; font-weight: bold; background: #dedede; }
|
|
.prim { color: #000; font-weight: bolder; background: #dedede; }
|
|
|
|
.tt { white-space: pre; font-family: monospace; background: #dedede; }
|
|
|
|
.h1, .h2, .h3, .h4 { white-space: normal; }
|
|
.h1 { font-size: 125%; }
|
|
.h2 { font-size: 120%; }
|
|
.h3 { font-size: 115%; }
|
|
.h4 { font-size: 110%; }
|
|
.hr { display: block; height: 2px; background: #000000; }
|
|
</style>
|
|
</head><body>
|
|
<p><span class="h1">A Quick Tutorial</span>
|
|
<br/><br/>
|
|
Programming in RETRO is all about creating words to solve
|
|
the problem at hand. Words operate on data, which can be
|
|
kept in memory or on the stack.
|
|
<br/><br/>
|
|
Let's look at this by solving a small problem: writing a
|
|
word to determine if a string is a palindrome.
|
|
<br/><br/>
|
|
A palindrome is a phrase which reads the same backward
|
|
and forward.
|
|
<br/><br/>
|
|
We first need a string to look at. Starting with something
|
|
easy:
|
|
<br/><br/>
|
|
<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='str'>'anna</span> </span><br/>
|
|
<span class="tt">```</span></span><br/><br/>
|
|
Looking in the Glossary, there is a <span class="tt">s:reverse</span> word for
|
|
reversing a string. We can find <span class="tt">dup</span> to copy a value, and
|
|
<span class="tt">s:eq?</span> to compare two strings. So testing:
|
|
<br/><br/>
|
|
<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='str'>'anna</span> <span class='prim'>dup</span> s:reverse s:eq? </span><br/>
|
|
<span class="tt">```</span></span><br/><br/>
|
|
This yields -1 (<span class="tt">TRUE</span>) as expected. So we can easily
|
|
name it:
|
|
<br/><br/>
|
|
<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='colon'>:palindrome?</span> <span class='prim'>dup</span> s:reverse s:eq? <span class='imm'>;</span> </span><br/>
|
|
<span class="tt">```</span></span><br/><br/>
|
|
Naming uses the <span class="tt">:</span> sigil to add a new word to the dictionary.
|
|
The words that make up the definition are then placed, with a
|
|
final word (<span class="tt">;</span>) ending the definition. We can then use this:
|
|
<br/><br/>
|
|
<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='str'>'anna</span> palindrome? </span><br/>
|
|
<span class="tt">```</span></span><br/><br/>
|
|
Once defined there is no difference between our new word and
|
|
any of the words already provided by the RETRO system.
|
|
</p>
|
|
</body></html>
|