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<title>BLisp: Lispっぽい静的型付け言語</title>
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<body class="article">
<div id="header">
<h1>BLisp: Lispっぽい静的型付け言語</h1>
<div class="details">
<span id="author" class="author">Yuuki Takano</span><br>
<span id="email" class="email"><a href="mailto:ytakano@wide.ad.jp">ytakano@wide.ad.jp</a></span><br>
<span id="revnumber">version 0.4.0,</span>
<span id="revdate">2023-02</span>
</div>
<div id="toc" class="toc">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_特徴">1. 特徴</a></li>
<li><a href="#_値">2. 値</a></li>
<li><a href="#_基本型">3. 基本型</a></li>
<li><a href="#_関数定義">4. 関数定義</a></li>
<li><a href="#_算術演算">5. 算術演算</a></li>
<li><a href="#_真偽値演算">6. 真偽値演算</a></li>
<li><a href="#_比較演算">7. 比較演算</a></li>
<li><a href="#_ビット演算">8. ビット演算</a></li>
<li><a href="#_数学的演算">9. 数学的演算</a></li>
<li><a href="#_代数的データ型">10. 代数的データ型</a></li>
<li><a href="#_ジェネリクス">11. ジェネリクス</a></li>
<li><a href="#_ジェネリック関数">12. ジェネリック関数</a></li>
<li><a href="#_if式">13. If式</a></li>
<li><a href="#_match式">14. Match式</a></li>
<li><a href="#_let式">15. Let式</a></li>
<li><a href="#_ラムダ式">16. ラムダ式</a></li>
<li><a href="#_マクロ">17. マクロ</a></li>
<li><a href="#_文字列と文字">18. 文字列と文字</a></li>
<li><a href="#_外部関数呼び出し">19. 外部関数呼び出し</a></li>
<li><a href="#_coqへのトランスパイラ_実験的">20. Coqへのトランスパイラ (実験的)</a></li>
<li><a href="#_例">21. 例</a>
<ul class="sectlevel2">
<li><a href="#_リバース">21.1. リバース</a></li>
<li><a href="#_filter">21.2. Filter</a></li>
<li><a href="#_階乗">21.3. 階乗</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p>BLispは静的型付けされたLispライクなプログラミング言語で、no_std環境用のエフェクトシステムを採用しています。BLispは関数型プログラミング言語の高階関数のような高階のRPCをサポートしています。</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://github.com/ytakano/blisp">GitHubリポジトリ</a></p>
</li>
<li>
<p><a href="https://crates.io/crates/blisp">BLispのcrates.io</a></p>
</li>
</ul>
</div>
<div class="paragraph">
<p>本リポジトリではライブラリクレートのみを提供しています。BLispを利用するには <a href="https://github.com/ytakano/blisp-repl">blisp-repl</a> か、おもちゃのOSである <a href="https://github.com/ytakano/baremetalisp">baremetalisp</a> を参照してください。</p>
</div>
<div class="paragraph">
<p><a href="https://ytakano.github.io/blisp/">English version is here.</a></p>
</div>
<div class="paragraph">
<div class="title">no_stdで動くBLisp</div>
<p><span class="image"><img src="https://cdn-ak.f.st-hatena.com/images/fotolife/y/ytakano/20210221/20210221155657.gif" alt="no_stdで動くBLisp"></span></p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_特徴">1. 特徴</h2>
<div class="sectionbody">
<div class="ulist">
<ul>
<li>
<p>代数的データ型</p>
</li>
<li>
<p>ジェネリクス</p>
</li>
<li>
<p>型推論</p>
</li>
<li>
<p>IOと純粋な関数を分離するためのエフェクトシステム</p>
</li>
<li>
<p>多倍長整数</p>
</li>
<li>
<p>no_std環境のサポート</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_値">2. 値</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">values</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-o">`</span><span class="tok-nv">A</span><span class="tok-o">`</span><span class="tok-w"> </span><span class="tok-c1">; 文字リテラル</span>
<span class="tok-s">"Hello"</span><span class="tok-w"> </span><span class="tok-c1">; 文字列リテラル</span>
<span class="tok-mi">144</span><span class="tok-w"> </span><span class="tok-c1">; 整数値</span>
<span class="tok-nv">0xabcDEF</span><span class="tok-w"> </span><span class="tok-c1">; 16進数</span>
<span class="tok-nv">0o777</span><span class="tok-w"> </span><span class="tok-c1">; 8進数</span>
<span class="tok-nv">0b1001</span><span class="tok-w"> </span><span class="tok-c1">; 2進数</span>
<span class="tok-nv">true</span><span class="tok-w"> </span><span class="tok-c1">; 真偽値</span>
<span class="tok-nv">false</span><span class="tok-w"> </span><span class="tok-c1">; 真偽値</span>
<span class="tok-nv">[true</span><span class="tok-w"> </span><span class="tok-nv">10]</span><span class="tok-w"> </span><span class="tok-c1">; タプル</span>
<span class="tok-nv">[]</span><span class="tok-w"> </span><span class="tok-c1">; 空のタプル</span>
<span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; リスト</span>
<span class="tok-o">'</span><span class="tok-p">()</span><span class="tok-w"> </span><span class="tok-c1">; 空のリスト、Nil</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_基本型">3. 基本型</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">types</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-nv">Char</span><span class="tok-w"> </span><span class="tok-c1">; 文字型</span>
<span class="tok-nv">String</span><span class="tok-w"> </span><span class="tok-c1">; 文字列型</span>
<span class="tok-nv">Int</span><span class="tok-w"> </span><span class="tok-c1">; 整数型</span>
<span class="tok-nv">Bool</span><span class="tok-w"> </span><span class="tok-c1">; 真偽値型</span>
<span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; Int型のリスト型</span>
<span class="tok-nv">[Int</span><span class="tok-w"> </span><span class="tok-nv">Bool]</span><span class="tok-w"> </span><span class="tok-c1">; Int型とBool型のタプル型</span>
<span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Bool</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; Int型の値を2つとり、Bool型の値をリターンする純粋な関数</span>
<span class="tok-p">(</span><span class="tok-nv">IO</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">[]</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; Int型の値をとり[]をリターンするIOのある関数</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>PureとIOは関数の効果です。IO関数内では、Pure関数とIO関数の両方を呼び出すことができます。しかし、Pure関数内では、Pure関数の呼び出しのみ許可されています。</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_関数定義">4. 関数定義</h2>
<div class="sectionbody">
<div class="paragraph">
<p>関数はdefunやexportで定義することができます。"defun"はRustのeval関数からは呼び出せないローカル関数を定義します。</p>
</div>
<div class="paragraph">
<p>以下の2つの関数があるとしましょう。</p>
</div>
<div class="listingblock">
<div class="title">defun</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">defun</span><span class="tok-w"> </span><span class="tok-nv">double</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; 関数名がdoubleでxは引数</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; 関数の型</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; 関数の中身</span></code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">export</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nv">quad</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; 関数名がquadで引数はx</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; 関数の型</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">double</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">double</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">)))</span><span class="tok-w"> </span><span class="tok-c1">; 関数の中身</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>doubleはRustのevalからは呼び出せませんが、内部で定義された関数からは呼び出せます。quadはRustのevalから呼び出すことができ、内部的にdoubleを呼び出します。</p>
</div>
<div class="paragraph">
<p>これはRustで実際に行うコードです。</p>
</div>
<div class="listingblock">
<div class="title">Rust’s eval</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="rust"><span></span><span class="tok-k">use</span><span class="tok-w"> </span><span class="tok-n">blisp</span><span class="tok-p">;</span>
<span class="tok-k">fn</span> <span class="tok-nf">eval</span><span class="tok-p">(</span><span class="tok-n">e</span>: <span class="tok-kp">&</span><span class="tok-kt">str</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">ctx</span>: <span class="tok-kp">&</span><span class="tok-nc">blisp</span>::<span class="tok-n">semantics</span>::<span class="tok-n">Context</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-c1">// evaluate expressions</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">exprs</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-k">match</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">eval</span><span class="tok-p">(</span><span class="tok-n">e</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">ctx</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-nb">Ok</span><span class="tok-p">(</span><span class="tok-n">es</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-o">=></span><span class="tok-w"> </span><span class="tok-n">es</span><span class="tok-p">,</span>
<span class="tok-w"> </span><span class="tok-nb">Err</span><span class="tok-p">(</span><span class="tok-n">err</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-o">=></span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-fm">println!</span><span class="tok-p">(</span><span class="tok-s">"error:{}:{}: {}"</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">err</span><span class="tok-p">.</span><span class="tok-n">pos</span><span class="tok-p">.</span><span class="tok-n">line</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">err</span><span class="tok-p">.</span><span class="tok-n">pos</span><span class="tok-p">.</span><span class="tok-n">column</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">err</span><span class="tok-p">.</span><span class="tok-n">msg</span><span class="tok-p">);</span>
<span class="tok-w"> </span><span class="tok-k">return</span><span class="tok-p">;</span>
<span class="tok-w"> </span><span class="tok-p">}</span>
<span class="tok-w"> </span><span class="tok-p">};</span>
<span class="tok-w"> </span><span class="tok-k">for</span><span class="tok-w"> </span><span class="tok-n">r</span><span class="tok-w"> </span><span class="tok-k">in</span><span class="tok-w"> </span><span class="tok-n">exprs</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-k">match</span><span class="tok-w"> </span><span class="tok-n">r</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-nb">Ok</span><span class="tok-p">(</span><span class="tok-n">msg</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-o">=></span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-fm">println!</span><span class="tok-p">(</span><span class="tok-s">"{}"</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">msg</span><span class="tok-p">);</span>
<span class="tok-w"> </span><span class="tok-p">}</span>
<span class="tok-w"> </span><span class="tok-nb">Err</span><span class="tok-p">(</span><span class="tok-n">msg</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-o">=></span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-fm">println!</span><span class="tok-p">(</span><span class="tok-s">"error: {}"</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">msg</span><span class="tok-p">);</span>
<span class="tok-w"> </span><span class="tok-p">}</span>
<span class="tok-w"> </span><span class="tok-p">}</span>
<span class="tok-w"> </span><span class="tok-p">}</span>
<span class="tok-p">}</span>
<span class="tok-k">fn</span> <span class="tok-nf">main</span><span class="tok-p">()</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-c1">// internal code</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">code</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-s">"</span>
<span class="tok-s">(defun double (x) ; 関数名がdoubleでxは引数</span>
<span class="tok-s"> (Pure (-> (Int) Int)) ; 関数の型</span>
<span class="tok-s"> (* 2 x)) ; 関数の中身</span>
<span class="tok-s">(export quad (x) ; 関数名がquadで引数はx</span>
<span class="tok-s"> (Pure (-> (Int) Int)) ; 関数の型</span>
<span class="tok-s"> (double (double x))) ; 関数の中身</span>
<span class="tok-s">"</span><span class="tok-p">;</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">exprs</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">init</span><span class="tok-p">(</span><span class="tok-n">code</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-fm">vec!</span><span class="tok-p">[]).</span><span class="tok-n">unwrap</span><span class="tok-p">();</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">ctx</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">typing</span><span class="tok-p">(</span><span class="tok-n">exprs</span><span class="tok-p">).</span><span class="tok-n">unwrap</span><span class="tok-p">();</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">e</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-s">"(double 10) ; エラー"</span><span class="tok-p">;</span>
<span class="tok-w"> </span><span class="tok-n">eval</span><span class="tok-p">(</span><span class="tok-n">e</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-o">&</span><span class="tok-n">ctx</span><span class="tok-p">);</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">e</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-s">"(quad 10) ; OK"</span><span class="tok-p">;</span>
<span class="tok-w"> </span><span class="tok-n">eval</span><span class="tok-p">(</span><span class="tok-n">e</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-o">&</span><span class="tok-n">ctx</span><span class="tok-p">);</span>
<span class="tok-p">}</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>このコードは以下のように出力します。</p>
</div>
<div class="literalblock">
<div class="content">
<pre>error:0:1: Typing Error: double is not defined
40</pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_算術演算">5. 算術演算</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">基本</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (Int Int) Int))</span>
<span class="tok-p">(</span><span class="tok-nb">+</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb">-</span><span class="tok-w"> </span><span class="tok-mi">30</span><span class="tok-w"> </span><span class="tok-mi">40</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-mi">6</span><span class="tok-w"> </span><span class="tok-mi">100</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb">/</span><span class="tok-w"> </span><span class="tok-mi">100</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nv">%</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-p">)</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_真偽値演算">6. 真偽値演算</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">logical</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (Bool Bool) Bool))</span>
<span class="tok-p">(</span><span class="tok-nb">and</span><span class="tok-w"> </span><span class="tok-nv">true</span><span class="tok-w"> </span><span class="tok-nv">false</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb">or</span><span class="tok-w"> </span><span class="tok-nv">true</span><span class="tok-w"> </span><span class="tok-nv">false</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nv">xor</span><span class="tok-w"> </span><span class="tok-nv">true</span><span class="tok-w"> </span><span class="tok-nv">false</span><span class="tok-p">)</span></code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">negation</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (Bool) Bool))</span>
<span class="tok-p">(</span><span class="tok-nb">not</span><span class="tok-w"> </span><span class="tok-nv">true</span><span class="tok-p">)</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_比較演算">7. 比較演算</h2>
<div class="sectionbody">
<div class="paragraph">
<p>=, !=, <, >, <=, >= といった関数は、同じ型の2つの値に対して適用できます。</p>
</div>
<div class="listingblock">
<div class="title">comparison between 2 values whose types are same</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (t t) Bool))</span>
<span class="tok-p">(</span><span class="tok-nb">=</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; true</span>
<span class="tok-p">(</span><span class="tok-nv">!=</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; false</span>
<span class="tok-p">(</span><span class="tok-nb">=</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; true</span>
<span class="tok-p">(</span><span class="tok-nb">=</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; false</span>
<span class="tok-p">(</span><span class="tok-nb"><</span><span class="tok-w"> </span><span class="tok-mi">6</span><span class="tok-w"> </span><span class="tok-mi">7</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb">></span><span class="tok-w"> </span><span class="tok-mi">6</span><span class="tok-w"> </span><span class="tok-mi">7</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb"><=</span><span class="tok-w"> </span><span class="tok-mi">30</span><span class="tok-w"> </span><span class="tok-mi">40</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb">>=</span><span class="tok-w"> </span><span class="tok-mi">30</span><span class="tok-w"> </span><span class="tok-mi">40</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb"><</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-w"> </span><span class="tok-s">"World"</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nb"><=</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><em>eq</em>, <em>neq</em>, <em>lt</em>, <em>gt</em>, <em>leq</em>, <em>geq</em> といった関数は、異なる型同士の値でも比較可能です。</p>
</div>
<div class="listingblock">
<div class="title">comparison between any 2 values</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (t1 t1) Bool))</span>
<span class="tok-p">(</span><span class="tok-nv">geq</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; (Some 1)は"Hello"より大きい、もしくは等しいか？</span>
<span class="tok-p">(</span><span class="tok-nb">eq</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-w"> </span><span class="tok-mi">100</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; "Hello"と100は等しいか？</span>
<span class="tok-p">(</span><span class="tok-nv">neq</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-w"> </span><span class="tok-mi">100</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; "Hello"と100は等しくないか？</span>
<span class="tok-p">(</span><span class="tok-nv">lt</span><span class="tok-w"> </span><span class="tok-mi">100</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; 100は(Some 20)より小さいか？</span>
<span class="tok-p">(</span><span class="tok-nv">gt</span><span class="tok-w"> </span><span class="tok-mi">200</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; 200は"Hello"より大きいか？</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_ビット演算">8. ビット演算</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">band</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; ビット積</span>
<span class="tok-p">(</span><span class="tok-nv">band</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; ビット積</span>
<span class="tok-p">(</span><span class="tok-nv">bor</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; ビット和</span>
<span class="tok-p">(</span><span class="tok-nv">bor</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; ビット和</span>
<span class="tok-p">(</span><span class="tok-nv">bxor</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; ビット排他的論理和</span></code></pre>
</div>
</div>
<div class="listingblock">
<div class="title">ビットシフト</div>
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (Int Int) (Option Int)))</span>
<span class="tok-p">(</span><span class="tok-nv"><<</span><span class="tok-w"> </span><span class="tok-mi">8</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; (Some 128)</span>
<span class="tok-p">(</span><span class="tok-nv">>></span><span class="tok-w"> </span><span class="tok-mi">128</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; (Some 8)</span>
<span class="tok-p">(</span><span class="tok-nv">>></span><span class="tok-w"> </span><span class="tok-mi">-128</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; (Some -8)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>2番目の引数が2<sup>64</sup>以上の場合はNoneをリターンします。</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_数学的演算">9. 数学的演算</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (Int Int) (Option Int)))</span>
<span class="tok-p">(</span><span class="tok-nv">pow</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; (Some 100000000000000000000) namely 10^20</span>
<span class="tok-c1">; (Pure (-> (Int) (Option Int)))</span>
<span class="tok-p">(</span><span class="tok-nb">sqrt</span><span class="tok-w"> </span><span class="tok-mi">16</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; (Some 4)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>powの指数部が2<sup>32</sup>以上の場合は、powはNoneをリターンします。</p>
</div>
<div class="paragraph">
<p>sqrtの引数が0以下の場合は、sqrtはNoneをリターンします。</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_代数的データ型">10. 代数的データ型</h2>
<div class="sectionbody">
<div class="paragraph">
<p>代数的データ型は以下のように定義できます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; in BLisp</span>
<span class="tok-p">(</span><span class="tok-nv">data</span><span class="tok-w"> </span><span class="tok-nv">Gender</span><span class="tok-w"> </span><span class="tok-c1">; 型名</span>
<span class="tok-w"> </span><span class="tok-nv">Male</span><span class="tok-w"> </span><span class="tok-c1">; 値</span>
<span class="tok-w"> </span><span class="tok-nv">Female</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; 値</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>型名とその値の最初の文字は大文字でなければなりません。これはRustの以下のコードと同等です。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="rust"><span></span><span class="tok-c1">// in Rust</span>
<span class="tok-k">enum</span> <span class="tok-nc">Gender</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-n">Male</span><span class="tok-p">,</span>
<span class="tok-w"> </span><span class="tok-n">Female</span>
<span class="tok-p">}</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>各要素は以下のような値を持つことができます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; in BLisp</span>
<span class="tok-p">(</span><span class="tok-nv">data</span><span class="tok-w"> </span><span class="tok-nv">Dim2</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Dim2</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; Dim2は2つのInt型の値を持つ</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>Dim2は以下のようにインスタンス化することができます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">Dim2</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>この型はRustの以下の型と同等です。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="rust"><span></span><span class="tok-c1">// in Rust</span>
<span class="tok-k">use</span><span class="tok-w"> </span><span class="tok-n">num_bigint</span>::<span class="tok-n">BigInt</span><span class="tok-p">;</span>
<span class="tok-k">enum</span> <span class="tok-nc">Dim2</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-n">Dim2</span><span class="tok-p">(</span><span class="tok-n">BigInt</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">BigInt</span><span class="tok-p">)</span>
<span class="tok-p">}</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_ジェネリクス">11. ジェネリクス</h2>
<div class="sectionbody">
<div class="paragraph">
<p>Option型とResult型は内部で定義されています。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">data</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Option</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-nv">None</span><span class="tok-p">)</span>
<span class="tok-p">(</span><span class="tok-nv">data</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Result</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-w"> </span><span class="tok-nv">e</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Ok</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Err</span><span class="tok-w"> </span><span class="tok-nv">e</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><em>t</em> と <em>e</em> は型変数です。このコードは、Rustの以下のコードと同等です。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="rust"><span></span><span class="tok-c1">// in Rust</span>
<span class="tok-k">enum</span> <span class="tok-nb">Option</span><span class="tok-o"><</span><span class="tok-n">T</span><span class="tok-o">></span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-nb">Some</span><span class="tok-p">(</span><span class="tok-n">T</span><span class="tok-p">),</span>
<span class="tok-w"> </span><span class="tok-nb">None</span><span class="tok-p">,</span>
<span class="tok-p">}</span>
<span class="tok-k">enum</span> <span class="tok-nb">Result</span><span class="tok-o"><</span><span class="tok-n">T</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">E</span><span class="tok-o">></span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-nb">Ok</span><span class="tok-p">(</span><span class="tok-n">T</span><span class="tok-p">),</span>
<span class="tok-w"> </span><span class="tok-nb">Err</span><span class="tok-p">(</span><span class="tok-n">E</span><span class="tok-p">),</span>
<span class="tok-p">}</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>リスト型は以下のような組み込み型です。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">data</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">List</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">List</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-no">Nil</span><span class="tok-p">)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>したがって、以下の2つのリストは等価です。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-w"> </span><span class="tok-no">Nil</span><span class="tok-p">)))</span>
<span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-p">)</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_ジェネリック関数">12. ジェネリック関数</h2>
<div class="sectionbody">
<div class="paragraph">
<p><em>car</em> と <em>cdr</em> は内部的に定義されたジェネリック関数です。これらの定義は以下の通りです。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nb">car</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-no">t</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Option</span><span class="tok-w"> </span><span class="tok-no">t</span><span class="tok-p">)))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-nv">x</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-nv">_</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-nv">None</span><span class="tok-p">)))</span>
<span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nb">cdr</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-no">t</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-no">t</span><span class="tok-p">)))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-nv">x</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">())))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>t_は型変数です。これらの関数は以下のように使うことができます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">car</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">3</span><span class="tok-w"> </span><span class="tok-mi">8</span><span class="tok-w"> </span><span class="tok-mi">9</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; returns (Some 3)</span>
<span class="tok-p">(</span><span class="tok-nb">cdr</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">8</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; returns '(10 4)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>通常変数と型変数の最初の文字は小文字でなければなりません。</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_if式">13. If式</h2>
<div class="sectionbody">
<div class="paragraph">
<p>単純です.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-k">if</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb"><</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">())</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_match式">14. Match式</h2>
<div class="sectionbody">
<div class="paragraph">
<p>リストは以下のようにマッチさせることができます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-nv">_</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-o">'</span><span class="tok-p">()</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>この、</p>
</div>
<div class="literalblock">
<div class="content">
<pre>(Cons n _)</pre>
</div>
</div>
<div class="paragraph">
<p>という式はパターンです。
パターンが '(1 2 3) にマッチした場合、1は可変変数 <em>n</em> に代入されます。そうすると、<em>n</em> つまり1が返されます。</p>
</div>
<div class="paragraph">
<p>タプルのパターンマッチングの例です。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-nv">[1</span><span class="tok-w"> </span><span class="tok-nv">3]</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">[x</span><span class="tok-w"> </span><span class="tok-nv">y]</span><span class="tok-w"> </span><span class="tok-nv">[y</span><span class="tok-w"> </span><span class="tok-nv">x]</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>このコードはタプルの第1要素と第2要素を入れ替えます。</p>
</div>
<div class="paragraph">
<p>整数値はパターンマッチングにも使用できます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-mi">20</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-mi">20</span><span class="tok-w"> </span><span class="tok-nv">true</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-nv">false</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>より複雑な例としては、以下のようなものがあります。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-nv">[</span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">true]</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">[</span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">false]</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">[</span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">true]</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>BLispはパターンを網羅的にチェックします。そのため、以下のコードは拒否されます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-o">'</span><span class="tok-p">()</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">))</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_let式">15. Let式</h2>
<div class="sectionbody">
<div class="paragraph">
<p>変数のバインドには、以下のようにLet式を使用します。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-k">let</span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">y</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; x is 10, y is 20</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">))</span>
<span class="tok-p">(</span><span class="tok-k">let</span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">)))</span><span class="tok-w"> </span><span class="tok-c1">; x = 10, x = x * x, x = x * x</span>
<span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>また、以下のように分配束縛を行うこともできます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-k">let</span><span class="tok-w"> </span><span class="tok-p">(((</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Some</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-p">)))</span><span class="tok-w"> </span><span class="tok-c1">; x is 10</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">))</span>
<span class="tok-p">(</span><span class="tok-k">let</span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">[x</span><span class="tok-w"> </span><span class="tok-nv">y]</span><span class="tok-w"> </span><span class="tok-nv">[10</span><span class="tok-w"> </span><span class="tok-nv">20]</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; x is 10, y is 20</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">))</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_ラムダ式">16. ラムダ式</h2>
<div class="sectionbody">
<div class="paragraph">
<p>ラムダ式は以下のように定義されます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-k">lambda</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>このラムダは2つの整数を受け取り、それらの乗算を返します。これに引数を適用するのは次のように簡単に行えます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">((</span><span class="tok-k">lambda</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-mi">10</span><span class="tok-w"> </span><span class="tok-mi">20</span><span class="tok-p">)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>すべてのラムダ式は純粋です。よって、ラムダ式からIO関数を呼び出すことはできません。</p>
</div>
<div class="paragraph">
<p><em>map</em> と <em>fold</em> 関数は内部的に以下のように定義されています。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nb">map</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">a</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">b</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-nv">a</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-nv">b</span><span class="tok-p">)))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-nv">x</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-nv">h</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-nv">h</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">map</span><span class="tok-w"> </span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">)))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">())))</span>
<span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nv">fold</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-nv">init</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">a</span><span class="tok-w"> </span><span class="tok-nv">b</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">b</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-nv">b</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-nv">a</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-nv">b</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">match</span><span class="tok-w"> </span><span class="tok-nv">x</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Cons</span><span class="tok-w"> </span><span class="tok-nv">h</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">fold</span><span class="tok-w"> </span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-nv">h</span><span class="tok-w"> </span><span class="tok-nv">init</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-nv">init</span><span class="tok-p">)))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><em>map</em> を使うと、以下のようにリストの要素に関数を適用することができます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; それぞれをの要素を2乗</span>
<span class="tok-p">(</span><span class="tok-k">let</span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">l</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-k">lambda</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-p">))))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">map</span><span class="tok-w"> </span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><em>fold</em> を使用して、リストの要素にまたがって計算することができます。例えば、合計は以下のように計算できます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; 合計</span>
<span class="tok-p">(</span><span class="tok-k">let</span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">l</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">20</span><span class="tok-w"> </span><span class="tok-mi">50</span><span class="tok-w"> </span><span class="tok-mi">60</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-k">lambda</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">+</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-nv">y</span><span class="tok-p">))))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">fold</span><span class="tok-w"> </span><span class="tok-nv">f</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-w"> </span><span class="tok-nv">l</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; 0 is an initial value</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>当然、これは以下のようにも記述できます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; summation</span>
<span class="tok-p">(</span><span class="tok-nv">fold</span><span class="tok-w"> </span><span class="tok-nb">+</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">20</span><span class="tok-w"> </span><span class="tok-mi">50</span><span class="tok-w"> </span><span class="tok-mi">60</span><span class="tok-p">))</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_マクロ">17. マクロ</h2>
<div class="sectionbody">
<div class="paragraph">
<p>マクロは <code>macro</code> で定義できます。
各ルールはパターンとテンプレートの組からなり、最初に一致したルールが展開されます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">macro</span><span class="tok-w"> </span><span class="tok-nv">add</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">add</span><span class="tok-w"> </span><span class="tok-nv">$e1</span><span class="tok-w"> </span><span class="tok-nv">$e2</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">+</span><span class="tok-w"> </span><span class="tok-nv">$e1</span><span class="tok-w"> </span><span class="tok-nv">$e2</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">add</span><span class="tok-w"> </span><span class="tok-nv">$e1</span><span class="tok-w"> </span><span class="tok-nv">$e2</span><span class="tok-w"> </span><span class="tok-nv">$e3</span><span class="tok-w"> </span><span class="tok-o">...</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">+</span><span class="tok-w"> </span><span class="tok-nv">$e1</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">add</span><span class="tok-w"> </span><span class="tok-nv">$e2</span><span class="tok-w"> </span><span class="tok-nv">$e3</span><span class="tok-w"> </span><span class="tok-o">...</span><span class="tok-p">))))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><code>$</code> で始まる識別子はパターン変数です。
パターン変数には、マクロ呼び出し側で一致した式がそのまま代入されます。
<code>…​</code> は、パターン変数やテンプレート断片の後ろに置くことで、残りの引数を可変長部分としてまとめて扱えます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">add</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; 3</span>
<span class="tok-p">(</span><span class="tok-nv">add</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-w"> </span><span class="tok-mi">5</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; 15</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>マクロは局所変数を導入する式も生成できます。
たとえば、一時変数を含むラムダ式は以下のように書けます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">macro</span><span class="tok-w"> </span><span class="tok-nv">with_tmp</span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">_</span><span class="tok-w"> </span><span class="tok-nv">$x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-k">lambda</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">tmp</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">+</span><span class="tok-w"> </span><span class="tok-nv">tmp</span><span class="tok-w"> </span><span class="tok-nv">$x</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)))</span>
<span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nv">test</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">tmp</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">with_tmp</span><span class="tok-w"> </span><span class="tok-nv">tmp</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>BLispのマクロは、テンプレートが導入する局所 binder に対して衛生的です。
<code>lambda</code> の引数、<code>let</code> の束縛、<code>match</code> のパターン変数は展開時に fresh な内部名へ自動的にリネームされるため、呼び出し側の同名変数を変数捕捉しません。
一方で、<code>defun</code>、<code>export</code>、<code>data</code> のようなトップレベル名は自動では改名されません。</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_文字列と文字">18. 文字列と文字</h2>
<div class="sectionbody">
<div class="paragraph">
<p><em>chars</em> はStringから(List Char)へ変換します。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> (String) (List Char)))</span>
<span class="tok-p">(</span><span class="tok-nv">chars</span><span class="tok-w"> </span><span class="tok-s">"Hello"</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-c1">; '(`H` `e` `l` `l` `o`)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><em>str</em> は(List Char)からStringへ変換します。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-c1">; (Pure (-> ((List Char)) String))</span>
<span class="tok-p">(</span><span class="tok-nv">str</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-o">`</span><span class="tok-nv">H</span><span class="tok-o">`</span><span class="tok-w"> </span><span class="tok-o">`</span><span class="tok-nv">e</span><span class="tok-o">`</span><span class="tok-w"> </span><span class="tok-o">`</span><span class="tok-nv">l</span><span class="tok-o">`</span><span class="tok-w"> </span><span class="tok-o">`</span><span class="tok-nv">l</span><span class="tok-o">`</span><span class="tok-w"> </span><span class="tok-o">`</span><span class="tok-nv">o</span><span class="tok-o">`</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; "Hello"</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_外部関数呼び出し">19. 外部関数呼び出し</h2>
<div class="sectionbody">
<div class="paragraph">
<p><em>blisp::embedded</em> は、外部関数呼び出し用のマクロです。
このマクロを利用すると、Rustの関数をBLispから容易に呼び出せるようになります。</p>
</div>
<div class="paragraph">
<p>たとえば、はじめに、Rustの関数を以下のように定義します。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="rust"><span></span><span class="tok-k">use</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">embedded</span><span class="tok-p">;</span>
<span class="tok-k">use</span><span class="tok-w"> </span><span class="tok-n">num_bigint</span>::<span class="tok-p">{</span><span class="tok-n">BigInt</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">ToBigInt</span><span class="tok-p">};</span>
<span class="tok-cp">#[embedded]</span>
<span class="tok-k">fn</span> <span class="tok-nf">add_four_ints</span><span class="tok-p">(</span><span class="tok-n">a</span>: <span class="tok-nc">BigInt</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">b</span>: <span class="tok-p">(</span><span class="tok-n">BigInt</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">BigInt</span><span class="tok-p">),</span><span class="tok-w"> </span><span class="tok-n">c</span>: <span class="tok-nb">Option</span><span class="tok-o"><</span><span class="tok-n">BigInt</span><span class="tok-o">></span><span class="tok-p">)</span><span class="tok-w"> </span>-> <span class="tok-nb">Result</span><span class="tok-o"><</span><span class="tok-n">BigInt</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-nb">String</span><span class="tok-o">></span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-k">mut</span><span class="tok-w"> </span><span class="tok-n">result</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">a</span><span class="tok-w"> </span><span class="tok-o">+</span><span class="tok-w"> </span><span class="tok-n">b</span><span class="tok-p">.</span><span class="tok-mi">0</span><span class="tok-w"> </span><span class="tok-o">+</span><span class="tok-w"> </span><span class="tok-n">b</span><span class="tok-p">.</span><span class="tok-mi">1</span><span class="tok-p">;</span>
<span class="tok-w"> </span><span class="tok-k">if</span><span class="tok-w"> </span><span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-nb">Some</span><span class="tok-p">(</span><span class="tok-n">n</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">c</span><span class="tok-w"> </span><span class="tok-p">{</span>
<span class="tok-w"> </span><span class="tok-n">result</span><span class="tok-w"> </span><span class="tok-o">+=</span><span class="tok-w"> </span><span class="tok-n">n</span><span class="tok-p">;</span>
<span class="tok-w"> </span><span class="tok-p">}</span>
<span class="tok-w"> </span><span class="tok-nb">Ok</span><span class="tok-p">(</span><span class="tok-n">result</span><span class="tok-p">)</span>
<span class="tok-p">}</span></code></pre>
</div>
</div>
<div class="paragraph">
<p><em>blisp::embedded</em> マクロは外部関数呼び出し用の型定義を生成します。
この関数は、以下のようにBLispから呼び出せます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nv">call_add_four_ints</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">n</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">IO</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Option</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Result</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-w"> </span><span class="tok-nv">String</span><span class="tok-p">)))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">add_four_ints</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-nv">[2</span><span class="tok-w"> </span><span class="tok-nv">3]</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>外部関数を登録するためには、以下のように、 <em>embedded</em> によって生成される型定義のベクタを
<em>blisp::init</em> に渡します。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="rust"><span></span><span class="tok-c1">// add_for_ints</span>
<span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">code</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-s">"(export call_add_four_ints (n)</span>
<span class="tok-s"> (IO (-> ((Option Int)) (Result Int String)))</span>
<span class="tok-s"> (add_four_ints 1 [2 3] n)</span>
<span class="tok-s">)"</span><span class="tok-p">;</span>
<span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">exprs</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">init</span><span class="tok-p">(</span><span class="tok-n">code</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-fm">vec!</span><span class="tok-p">[</span><span class="tok-nb">Box</span>::<span class="tok-n">new</span><span class="tok-p">(</span><span class="tok-n">AddFourInts</span><span class="tok-p">)]).</span><span class="tok-n">unwrap</span><span class="tok-p">();</span>
<span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">ctx</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">typing</span><span class="tok-p">(</span><span class="tok-n">exprs</span><span class="tok-p">).</span><span class="tok-n">unwrap</span><span class="tok-p">();</span>
<span class="tok-kd">let</span><span class="tok-w"> </span><span class="tok-n">result</span><span class="tok-w"> </span><span class="tok-o">=</span><span class="tok-w"> </span><span class="tok-n">blisp</span>::<span class="tok-n">eval</span><span class="tok-p">(</span><span class="tok-s">"(call_add_four_ints (Some 4))"</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-o">&</span><span class="tok-n">ctx</span><span class="tok-p">).</span><span class="tok-n">unwrap</span><span class="tok-p">();</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>ここでは、関数名が <em>add_four_ints</em> のため、そのキャメルケースの <em>AddFourInts</em>
を <em>Box</em> と <em>Vec</em> に包んで <em>blisp::init</em> に渡さなければなりません。</p>
</div>
<div class="paragraph">
<p>Rustの外部関数は以下に示される型のみ引数と返り値で利用可能です。
<em>Vec<u64></em> のような他の型はサポート外ですが、
<em>Vec<Option<bool>></em> のような型はOKです。
BLispとRustの間の型変換は <em>embedded</em> マクロが生成する関数によって自動的に行われます。</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 1. Type Conversion between BLisp and Rust</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-left valign-top">BLisp</th>
<th class="tableblock halign-left valign-top">Rust</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>Int</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>BigInt</em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>Bool</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>bool</em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>Char</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>char</em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>String</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>String</em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>'(T)</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>Vec<T></em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>[T0, T1]</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>(T0, T1)</em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>(Option T)</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>Option<T></em></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>(Result T E)</em></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><em>Result<T, E></em></p></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="sect1">
<h2 id="_coqへのトランスパイラ_実験的">20. Coqへのトランスパイラ (実験的)</h2>
<div class="sectionbody">
<div class="paragraph">
<p>BLispは実験的にCoqへのトランスパイラを実装しています。
トランスパイラは、以下のように <em>blisp::transpile</em> を呼び出すことで実行されます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="coq"><span></span><span class="tok-k">let</span> <span class="tok-n">expr</span> <span class="tok-o">=</span> <span class="tok-s2">"</span>
<span class="tok-s2">(defun snoc (l y)</span>
<span class="tok-s2">(Pure (-> (</span>
<span class="tok-s2"> '(t) t)</span>
<span class="tok-s2">'(t)))</span>
<span class="tok-s2">(match l</span>
<span class="tok-s2"> (nil (Cons y nil))</span>
<span class="tok-s2"> ((Cons h b) (Cons h (snoc b y)))))</span>
<span class="tok-s2">(defun rev (l)</span>
<span class="tok-s2">(Pure (-> (</span>
<span class="tok-s2"> '(t))</span>
<span class="tok-s2">'(t)))</span>
<span class="tok-s2">(match l</span>
<span class="tok-s2"> (nil nil)</span>
<span class="tok-s2"> ((Cons h t) (snoc (rev t) h))))</span>
<span class="tok-s2"> "</span><span class="tok-o">;</span>
<span class="tok-k">let</span> <span class="tok-n">exprs</span> <span class="tok-o">=</span> <span class="tok-n">blisp</span><span class="tok-o">::</span><span class="tok-n">init</span><span class="tok-o">(</span><span class="tok-n">expr</span><span class="tok-o">,</span> <span class="tok-n">vec</span><span class="tok-o">!</span><span class="tok-bp">[]</span><span class="tok-o">).</span><span class="tok-n">unwrap</span><span class="tok-bp">()</span><span class="tok-o">;</span>
<span class="tok-k">let</span> <span class="tok-n">ctx</span> <span class="tok-o">=</span> <span class="tok-n">blisp</span><span class="tok-o">::</span><span class="tok-n">typing</span><span class="tok-o">(</span><span class="tok-n">exprs</span><span class="tok-o">).</span><span class="tok-n">unwrap</span><span class="tok-bp">()</span><span class="tok-o">;</span>
<span class="tok-n">println</span><span class="tok-o">!(</span><span class="tok-s2">"{}"</span><span class="tok-o">,</span> <span class="tok-n">blisp</span><span class="tok-o">::</span><span class="tok-n">transpile</span><span class="tok-o">(&</span><span class="tok-n">ctx</span><span class="tok-o">));</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>これは以下のようなCoqのコードを出力します。
この出力には、BLispのプレリュードも含まれます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="coq"><span></span><span class="tok-kn">Require</span> <span class="tok-kn">Import</span> <span class="tok-n">ZArith</span><span class="tok-o">.</span>
<span class="tok-kn">Require</span> <span class="tok-kn">Import</span> <span class="tok-n">Coq.Lists.List</span><span class="tok-o">.</span>
<span class="tok-kn">Inductive</span> <span class="tok-n">Option</span> <span class="tok-o">(</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">):</span> <span class="tok-kt">Type</span> <span class="tok-o">:=</span>
<span class="tok-o">|</span> <span class="tok-n">Some</span> <span class="tok-o">(</span><span class="tok-n">x0</span><span class="tok-o">:</span> <span class="tok-n">t</span><span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-n">None</span><span class="tok-o">.</span>
<span class="tok-kn">Arguments</span> <span class="tok-n">Some</span><span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">}.</span>
<span class="tok-kn">Arguments</span> <span class="tok-n">None</span><span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">}.</span>
<span class="tok-kn">Inductive</span> <span class="tok-n">Result</span> <span class="tok-o">(</span><span class="tok-n">t</span> <span class="tok-n">e</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">):</span> <span class="tok-kt">Type</span> <span class="tok-o">:=</span>
<span class="tok-o">|</span> <span class="tok-n">Ok</span> <span class="tok-o">(</span><span class="tok-n">x0</span><span class="tok-o">:</span> <span class="tok-n">t</span><span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-n">Err</span> <span class="tok-o">(</span><span class="tok-n">x0</span><span class="tok-o">:</span> <span class="tok-n">e</span><span class="tok-o">).</span>
<span class="tok-kn">Arguments</span> <span class="tok-n">Ok</span><span class="tok-o">{</span><span class="tok-n">t</span> <span class="tok-n">e</span><span class="tok-o">}.</span>
<span class="tok-kn">Arguments</span> <span class="tok-n">Err</span><span class="tok-o">{</span><span class="tok-n">t</span> <span class="tok-n">e</span><span class="tok-o">}.</span>
<span class="tok-kn">Definition</span> <span class="tok-n">car</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">x</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">Option</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">x</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">n</span> <span class="tok-o">_)</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">Some</span> <span class="tok-n">n</span><span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-o">_</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">None</span><span class="tok-o">)</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Definition</span> <span class="tok-n">cdr</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">x</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">x</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-o">_</span> <span class="tok-n">l</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-n">l</span>
<span class="tok-o">|</span> <span class="tok-o">_</span> <span class="tok-o">=></span> <span class="tok-n">nil</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Definition</span> <span class="tok-n">filter</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">f</span><span class="tok-o">:</span> <span class="tok-n">t</span> <span class="tok-o">-></span> <span class="tok-n">bool</span><span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">x</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-o">(</span><span class="tok-n">reverse</span> <span class="tok-o">(</span><span class="tok-n">filter'</span> <span class="tok-n">f</span> <span class="tok-n">x</span> <span class="tok-n">nil</span> <span class="tok-o">)</span> <span class="tok-o">).</span>
<span class="tok-kn">Fixpoint</span> <span class="tok-n">filter'</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">f</span><span class="tok-o">:</span> <span class="tok-n">t</span> <span class="tok-o">-></span> <span class="tok-n">bool</span><span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">x</span> <span class="tok-n">l</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">x</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">a</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-k">match</span> <span class="tok-o">(</span><span class="tok-n">f</span> <span class="tok-n">h</span> <span class="tok-o">)</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-bp">true</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">filter'</span> <span class="tok-n">f</span> <span class="tok-n">a</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">l</span><span class="tok-o">)</span> <span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-bp">false</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">filter'</span> <span class="tok-n">f</span> <span class="tok-n">a</span> <span class="tok-n">l</span> <span class="tok-o">)</span>
<span class="tok-k">end</span>
<span class="tok-o">|</span> <span class="tok-o">_</span> <span class="tok-o">=></span> <span class="tok-n">l</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Fixpoint</span> <span class="tok-k">fold</span> <span class="tok-o">{</span><span class="tok-n">a</span> <span class="tok-n">b</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">f</span><span class="tok-o">:</span> <span class="tok-n">a</span> <span class="tok-o">-></span> <span class="tok-n">b</span> <span class="tok-o">-></span> <span class="tok-n">b</span><span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">init</span><span class="tok-o">:</span> <span class="tok-n">b</span><span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">x</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">a</span><span class="tok-o">):</span> <span class="tok-n">b</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">x</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">l</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-k">fold</span> <span class="tok-n">f</span> <span class="tok-o">(</span><span class="tok-n">f</span> <span class="tok-n">h</span> <span class="tok-n">init</span> <span class="tok-o">)</span> <span class="tok-n">l</span> <span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-o">_</span> <span class="tok-o">=></span> <span class="tok-n">init</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Fixpoint</span> <span class="tok-n">map</span> <span class="tok-o">{</span><span class="tok-n">a</span> <span class="tok-n">b</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">f</span><span class="tok-o">:</span> <span class="tok-n">a</span> <span class="tok-o">-></span> <span class="tok-n">b</span><span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">x</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">a</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">b</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">x</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">l</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-o">(</span><span class="tok-n">f</span> <span class="tok-n">h</span> <span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">map</span> <span class="tok-n">f</span> <span class="tok-n">l</span> <span class="tok-o">))</span>
<span class="tok-o">|</span> <span class="tok-o">_</span> <span class="tok-o">=></span> <span class="tok-n">nil</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Fixpoint</span> <span class="tok-n">rev</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">l</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">l</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-n">nil</span> <span class="tok-o">=></span> <span class="tok-n">nil</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">t</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">snoc</span> <span class="tok-o">(</span><span class="tok-n">rev</span> <span class="tok-n">t</span> <span class="tok-o">)</span> <span class="tok-n">h</span> <span class="tok-o">)</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Definition</span> <span class="tok-n">reverse</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">x</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-o">(</span><span class="tok-n">reverse'</span> <span class="tok-n">x</span> <span class="tok-n">nil</span> <span class="tok-o">).</span>
<span class="tok-kn">Fixpoint</span> <span class="tok-n">reverse'</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">x</span> <span class="tok-n">l</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">x</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">a</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">reverse'</span> <span class="tok-n">a</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">l</span><span class="tok-o">)</span> <span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-o">_</span> <span class="tok-o">=></span> <span class="tok-n">l</span>
<span class="tok-k">end</span><span class="tok-o">.</span>
<span class="tok-kn">Fixpoint</span> <span class="tok-n">snoc</span> <span class="tok-o">{</span><span class="tok-n">t</span><span class="tok-o">:</span> <span class="tok-kt">Type</span><span class="tok-o">}</span> <span class="tok-o">(</span><span class="tok-n">l</span><span class="tok-o">:</span> <span class="tok-n">list</span> <span class="tok-n">t</span><span class="tok-o">)</span> <span class="tok-o">(</span><span class="tok-n">y</span><span class="tok-o">:</span> <span class="tok-n">t</span><span class="tok-o">):</span> <span class="tok-n">list</span> <span class="tok-n">t</span> <span class="tok-o">:=</span>
<span class="tok-k">match</span> <span class="tok-n">l</span> <span class="tok-k">with</span>
<span class="tok-o">|</span> <span class="tok-n">nil</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">y</span> <span class="tok-n">nil</span><span class="tok-o">)</span>
<span class="tok-o">|</span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-n">b</span><span class="tok-o">)</span> <span class="tok-o">=></span> <span class="tok-o">(</span><span class="tok-n">cons</span> <span class="tok-n">h</span> <span class="tok-o">(</span><span class="tok-n">snoc</span> <span class="tok-n">b</span> <span class="tok-n">y</span> <span class="tok-o">))</span>
<span class="tok-k">end</span><span class="tok-o">.</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>このトランスパイラは実験的なものであることに注意してください。
よって、いくつかの出力はCoqが解釈できません。
その場合は、手動でソースコードを修正してください。
簡単にできるはずです。</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_例">21. 例</h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_リバース">21.1. リバース</h3>
<div class="paragraph">
<p><em>reverse</em> は内部で定義されている関数です。この関数はリストを反転します。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">reverse</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-w"> </span><span class="tok-mi">5</span><span class="tok-w"> </span><span class="tok-mi">6</span><span class="tok-w"> </span><span class="tok-mi">7</span><span class="tok-w"> </span><span class="tok-mi">8</span><span class="tok-w"> </span><span class="tok-mi">9</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>このコードの出力は以下の通りです。</p>
</div>
<div class="literalblock">
<div class="content">
<pre>'(9 8 7 6 5 4 3 2 1)</pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_filter">21.2. Filter</h3>
<div class="paragraph">
<p><em>filter</em> は内部で定義されている関数です。この関数はリストの中身をフィルターします。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">filter</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-k">lambda</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">x</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">=</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">%</span><span class="tok-w"> </span><span class="tok-nv">x</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-mi">1</span><span class="tok-w"> </span><span class="tok-mi">2</span><span class="tok-w"> </span><span class="tok-mi">3</span><span class="tok-w"> </span><span class="tok-mi">4</span><span class="tok-w"> </span><span class="tok-mi">5</span><span class="tok-w"> </span><span class="tok-mi">6</span><span class="tok-w"> </span><span class="tok-mi">7</span><span class="tok-w"> </span><span class="tok-mi">8</span><span class="tok-w"> </span><span class="tok-mi">9</span><span class="tok-p">))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>このコードの出力は以下の通りです。</p>
</div>
<div class="literalblock">
<div class="content">
<pre>'(2 4 6 8)</pre>
</div>
</div>
<div class="paragraph">
<p><em>filter</em>' の型は以下の通りです。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span>
<span class="tok-w"> </span><span class="tok-p">((</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-no">t</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Bool</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; 関数を引数にとる</span>
<span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-no">t</span><span class="tok-p">))</span><span class="tok-w"> </span><span class="tok-c1">; リストを引数にとる</span>
<span class="tok-w"> </span><span class="tok-o">'</span><span class="tok-p">(</span><span class="tok-no">t</span><span class="tok-p">)))</span><span class="tok-w"> </span><span class="tok-c1">; リストをリターン</span></code></pre>
</div>
</div>
</div>
<div class="sect2">
<h3 id="_階乗">21.3. 階乗</h3>
<div class="paragraph">
<p>末尾呼び出し版の階乗関数は、以下のように実装できます。</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="lisp"><span></span><span class="tok-p">(</span><span class="tok-nb">export</span><span class="tok-w"> </span><span class="tok-nv">factorial</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">n</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">fact</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">))</span>
<span class="tok-p">(</span><span class="tok-nb">defun</span><span class="tok-w"> </span><span class="tok-nv">fact</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-nv">total</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Pure</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">-></span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">Int</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-nv">Int</span><span class="tok-p">))</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-k">if</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb"><=</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-mi">0</span><span class="tok-p">)</span>
<span class="tok-w"> </span><span class="tok-nv">total</span>
<span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nv">fact</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">-</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-mi">1</span><span class="tok-p">)</span><span class="tok-w"> </span><span class="tok-p">(</span><span class="tok-nb">*</span><span class="tok-w"> </span><span class="tok-nv">n</span><span class="tok-w"> </span><span class="tok-nv">total</span><span class="tok-p">))))</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>この関数は以下のように呼び出すことができます。</p>
</div>
<div class="literalblock">
<div class="content">
<pre>>> (factorial 10)
3628800
>>
>> (factorial 1000)
402387260077093773543702433923003985719374864210714632543799910429938512398629020592044208486969404800479988610197196058631666872994808558901323829669944590997424504087073759918823627727188732519779505950995276120874975462497043601418278094646496291056393887437886487337119181045825783647849977012476632889835955735432513185323958463075557409114262417474349347553428646576611667797396668820291207379143853719588249808126867838374559731746136085379534524221586593201928090878297308431392844403281231558611036976801357304216168747609675871348312025478589320767169132448426236131412508780208000261683151027341827977704784635868170164365024153691398281264810213092761244896359928705114964975419909342221566832572080821333186116811553615836546984046708975602900950537616475847728421889679646244945160765353408198901385442487984959953319101723355556602139450399736280750137837615307127761926849034352625200015888535147331611702103968175921510907788019393178114194545257223865541461062892187960223838971476088506276862967146674697562911234082439208160153780889893964518263243671616762179168909779911903754031274622289988005195444414282012187361745992642956581746628302955570299024324153181617210465832036786906117260158783520751516284225540265170483304226143974286933061690897968482590125458327168226458066526769958652682272807075781391858178889652208164348344825993266043367660176999612831860788386150279465955131156552036093988180612138558600301435694527224206344631797460594682573103790084024432438465657245014402821885252470935190620929023136493273497565513958720559654228749774011413346962715422845862377387538230483865688976461927383814900140767310446640259899490222221765904339901886018566526485061799702356193897017860040811889729918311021171229845901641921068884387121855646124960798722908519296819372388642614839657382291123125024186649353143970137428531926649875337218940694281434118520158014123344828015051399694290153483077644569099073152433278288269864602789864321139083506217095002597389863554277196742822248757586765752344220207573630569498825087968928162753848863396909959826280956121450994871701244516461260379029309120889086942028510640182154399457156805941872748998094254742173582401063677404595741785160829230135358081840096996372524230560855903700624271243416909004153690105933983835777939410970027753472000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
>>
>> (factorial 100)
93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
>>
>> (factorial 500)
1220136825991110068701238785423046926253574342803192842192413588385845373153881997605496447502203281863013616477148203584163378722078177200480785205159329285477907571939330603772960859086270429174547882424912726344305670173270769461062802310452644218878789465754777149863494367781037644274033827365397471386477878495438489595537537990423241061271326984327745715546309977202781014561081188373709531016356324432987029563896628911658974769572087926928871281780070265174507768410719624390394322536422605234945850129918571501248706961568141625359056693423813008856249246891564126775654481886506593847951775360894005745238940335798476363944905313062323749066445048824665075946735862074637925184200459369692981022263971952597190945217823331756934581508552332820762820023402626907898342451712006207714640979456116127629145951237229913340169552363850942885592018727433795173014586357570828355780158735432768888680120399882384702151467605445407663535984174430480128938313896881639487469658817504506926365338175055478128640000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000</pre>
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