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@abedra
abedra committed Jun 27, 2012
1 parent c808935 commit 2a7319a
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26 changes: 13 additions & 13 deletions bootstrapping-a-language.org
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Expand Up @@ -30,7 +30,7 @@
geeklisp>
#+end_src
* This is the true story... of several lines of code... picked to live in a REPL... to work together and have their lines executed... find out what happens when code stops being polite... and starts getting real... :slide:
* Everyone should try to write a language :slide:
* Everyone should write a language :slide:
* :slide:
file:lisplogo.png
* Peter Norvig :slide:
Expand Down Expand Up @@ -129,13 +129,13 @@ file:norvig.jpg
#+end_src
* Update eval to accept an env and repl to initialize an env :slide:
#+begin_src ruby
def eval(x, env)
return env[x] if x.is_a? Symbol
return x if !x.is_a? Array
case x[0]
when :quote then x[1..-1]
when :define then env[x[1]] = eval(x[2], env)
when :set! then env.set(x[1], eval(x[2], env))
def eval(symbol, env)
return env[symbol] if symbol.is_a? Symbol
return symbol if !symbol.is_a? Array
case symbol[0]
when :quote then symbol[1..-1]
when :define then env[symbol[1]] = eval(symbol[2], env)
when :set! then env.set(symbol[1], eval(symbol[2], env))
when :env then env
end
end
Expand Down Expand Up @@ -258,18 +258,18 @@ file:norvig.jpg
#+end_src
* We're almost there! Let's round things out :slide:
#+begin_src ruby
def eval(x, env)
def eval(symbol, env)
...
when :if
_, test, conseq, alt = x
_, test, conseq, alt = symbol
eval(eval(test, env) ? conseq : alt, env)
when :lambda
_, vars, exp = x
_, vars, exp = symbol
Proc.new{|*args| eval(exp, Env.new(vars, args, env))}
when :begin
x[1..-1].reduce([nil, env]){|val_env, exp| [eval(exp, val_env[1]), val_env[1]]}[0]
symbol[1..-1].reduce([nil, env]){|val_env, exp| [eval(exp, val_env[1]), val_env[1]]}[0]
else
exps = x.map{|exp| eval(exp, env)}
exps = symbol.map{|exp| eval(exp, env)}
exps[0].call(*exps[1..-1])
end
end
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32 changes: 16 additions & 16 deletions slides.html
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Expand Up @@ -7,7 +7,7 @@
<meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"/>
<meta name="title" content="Bootstrapping a Language"/>
<meta name="generator" content="Org-mode"/>
<meta name="generated" content="2012-06-27T09:06-0400"/>
<meta name="generated" content="2012-06-27T11:40-0400"/>
<meta name="author" content="Aaron Bedra"/>
<meta name="description" content=""/>
<meta name="keywords" content=""/>
Expand Down Expand Up @@ -37,7 +37,7 @@ <h2>Table of Contents</h2>
<li><a href="#sec-2">2 Once upon a time there was a REPL</a></li>
<li><a href="#sec-3">3 But that REPL didn't do much</a></li>
<li><a href="#sec-4">4 This is the true story&hellip; of several lines of code&hellip; picked to live in a REPL&hellip; to work together and have their lines executed&hellip; find out what happens when code stops being polite&hellip; and starts getting real&hellip;</a></li>
<li><a href="#sec-5">5 Everyone should try to write a language</a></li>
<li><a href="#sec-5">5 Everyone should write a language</a></li>
<li><a href="#sec-6">6 :slide:</a></li>
<li><a href="#sec-7">7 Peter Norvig</a></li>
<li><a href="#sec-8">8 The basics</a></li>
Expand Down Expand Up @@ -147,7 +147,7 @@ <h2 id="sec-4"><span class="section-number-2">4</span> This is the true story&he
</div>

<div id="outline-container-5" class="outline-2">
<h2 id="sec-5"><span class="section-number-2">5</span> Everyone should try to write a language &nbsp;&nbsp;&nbsp;<span class="tag"><span class="slide">slide</span></span></h2>
<h2 id="sec-5"><span class="section-number-2">5</span> Everyone should write a language &nbsp;&nbsp;&nbsp;<span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-5">

</div>
Expand Down Expand Up @@ -343,13 +343,13 @@ <h2 id="sec-15"><span class="section-number-2">15</span> Update eval to accept a



<pre class="src src-ruby"><span style="color: #7f007f;">def</span> <span style="color: #0000ff;">eval</span>(x, env)
<span style="color: #7f007f;">return</span> env[x] <span style="color: #7f007f;">if</span> x.is_a? <span style="color: #228b22;">Symbol</span>
<span style="color: #7f007f;">return</span> x <span style="color: #7f007f;">if</span> !x.is_a? <span style="color: #228b22;">Array</span>
<span style="color: #7f007f;">case</span> x[0]
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:quote</span> <span style="color: #7f007f;">then</span> x[1..-1]
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:define</span> <span style="color: #7f007f;">then</span> env[x[1]] = eval(x[2], env)
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:set!</span> <span style="color: #7f007f;">then</span> env.set(x[1], eval(x[2], env))
<pre class="src src-ruby"><span style="color: #7f007f;">def</span> <span style="color: #0000ff;">eval</span>(symbol, env)
<span style="color: #7f007f;">return</span> env[symbol] <span style="color: #7f007f;">if</span> symbol.is_a? <span style="color: #228b22;">Symbol</span>
<span style="color: #7f007f;">return</span> symbol <span style="color: #7f007f;">if</span> !symbol.is_a? <span style="color: #228b22;">Array</span>
<span style="color: #7f007f;">case</span> symbol[0]
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:quote</span> <span style="color: #7f007f;">then</span> symbol[1..-1]
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:define</span> <span style="color: #7f007f;">then</span> env[symbol[1]] = eval(symbol[2], env)
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:set!</span> <span style="color: #7f007f;">then</span> env.set(symbol[1], eval(symbol[2], env))
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:env</span> <span style="color: #7f007f;">then</span> env
<span style="color: #7f007f;">end</span>
<span style="color: #7f007f;">end</span>
Expand Down Expand Up @@ -542,18 +542,18 @@ <h2 id="sec-22"><span class="section-number-2">22</span> We're almost there! Let



<pre class="src src-ruby"><span style="color: #7f007f;">def</span> <span style="color: #0000ff;">eval</span>(x, env)
<pre class="src src-ruby"><span style="color: #7f007f;">def</span> <span style="color: #0000ff;">eval</span>(symbol, env)
...
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:if</span>
_, test, conseq, alt = x
_, test, conseq, alt = symbol
eval(eval(test, env) ? conseq : alt, env)
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:lambda</span>
_, vars, exp = x
_, vars, exp = symbol
<span style="color: #228b22;">Proc</span>.new{|*args| eval(exp, <span style="color: #228b22;">Env</span>.new(vars, args, env))}
<span style="color: #7f007f;">when</span> <span style="color: #008b8b;">:begin</span>
x[1..-1].reduce([<span style="color: #a0522d;">nil</span>, env]){|val_env, exp| [eval(exp, val_env[1]), val_env[1]]}[0]
symbol[1..-1].reduce([<span style="color: #a0522d;">nil</span>, env]){|val_env, exp| [eval(exp, val_env[1]), val_env[1]]}[0]
<span style="color: #7f007f;">else</span>
exps = x.map{|exp| eval(exp, env)}
exps = symbol.map{|exp| eval(exp, env)}
exps[0].call(*exps[1..-1])
<span style="color: #7f007f;">end</span>
<span style="color: #7f007f;">end</span>
Expand Down Expand Up @@ -1100,7 +1100,7 @@ <h2 id="sec-46"><span class="section-number-2">46</span> References &nbsp;&nbsp;
</div>

<div id="postamble">
<p class="date">Date: 2012-06-27T09:06-0400</p>
<p class="date">Date: 2012-06-27T11:40-0400</p>
<p class="author">Author: Aaron Bedra</p>
<p class="creator"><a href="http://orgmode.org">Org</a> version 7.8.10 with <a href="http://www.gnu.org/software/emacs/">Emacs</a> version 24</p>
<a href="http://validator.w3.org/check?uri=referer">Validate XHTML 1.0</a>
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