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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>CCCache (containers.data.CCCache)</title><link rel="stylesheet" href="../../odoc.css"/><meta charset="utf-8"/><meta name="viewport" content="width=device-width,initial-scale=1.0"/><meta name="generator" content="doc-ock-html v1.0.0-1-g1fc9bf0"/></head><body><nav id="top"><a href="../index.html">Up</a> — <span class="package">package <a href="../index.html">containers.data</a></span></nav><header><h1><span class="keyword">Module</span> <span class="module-path">CCCache</span></h1></header><h2>Caches</h2><p>Particularly useful for memoization. See <a href="index.html#val-with_cache">with_cache</a> and <a href="index.html#val-with_cache_rec">with_cache_rec</a>
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for more details.</p><ul class="at-tag"><li><span class="at-tag since">Since</span>: 0.6</li></ul><div class="spec type" id="type-equal"><a href="#type-equal" class="anchor"></a><div class="def type"><code><span class="keyword">type </span>'a equal</code><code><span class="keyword"> = </span><span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'a</span> <span class="keyword">‑></span> bool</code><code></code></div><div class="doc"></div></div><div class="spec type" id="type-hash"><a href="#type-hash" class="anchor"></a><div class="def type"><code><span class="keyword">type </span>'a hash</code><code><span class="keyword"> = </span><span class="type-var">'a</span> <span class="keyword">‑></span> int</code><code></code></div><div class="doc"></div></div><h3>Value interface</h3><p>Typical use case: one wants to memoize a function <code class="code">f : 'a -> 'b</code>. Code sample:
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</p><pre><code class="code"> let f x =
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print_endline "call f";
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x + 1;;
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let f' = with_cache (lru 256) f;;
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f' 0;; (* prints *)
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f' 1;; (* prints *)
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f' 0;; (* doesn't print, returns cached value *)</code></pre><ul class="at-tag"><li><span class="at-tag since">Since</span>: 0.6</li></ul><div class="spec type" id="type-t"><a href="#type-t" class="anchor"></a><div class="def type"><code><span class="keyword">type </span>('a, 'b) t</code><code></code><code></code></div><div class="doc"></div></div><div class="spec val" id="val-clear"><a href="#val-clear" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>clear : (<span class="type-var">_</span>, <span class="type-var">_</span>) <a href="index.html#type-t">t</a> <span class="keyword">‑></span> unit</code></div><div class="doc"><p>Clear the content of the cache.</p></div></div><div class="spec type" id="type-callback"><a href="#type-callback" class="anchor"></a><div class="def type"><code><span class="keyword">type </span>('a, 'b) callback</code><code><span class="keyword"> = </span>in_cache:bool <span class="keyword">‑></span> <span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span> <span class="keyword">‑></span> unit</code><code></code></div><div class="doc"><p>Type of the callback that is called once a cached value is found
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or not.
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Should never raise.</p><ul class="at-tag"><li><span class="at-tag parameter">Parameter</span> <span class="module-path">in_cache</span>: is <code class="code">true</code> if the value was in cache, <code class="code">false</code>
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if the value was just produced.</li><li><span class="at-tag since">Since</span>: 1.3</li></ul></div></div><div class="spec val" id="val-with_cache"><a href="#val-with_cache" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>with_cache : ?⁠cb:(<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-callback">callback</a> <span class="keyword">‑></span> (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a> <span class="keyword">‑></span> (<span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span>) <span class="keyword">‑></span> <span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span></code></div><div class="doc"><p><code class="code">with_cache c f</code> behaves like <code class="code">f</code>, but caches calls to <code class="code">f</code> in the
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cache <code class="code">c</code>. It always returns the same value as
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<code class="code">f x</code>, if <code class="code">f x</code> returns, or raise the same exception.
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However, <code class="code">f</code> may not be called if <code class="code">x</code> is in the cache.</p><ul class="at-tag"><li><span class="at-tag parameter">Parameter</span> <span class="module-path">cb</span>: called after the value is generated or retrieved.</li></ul></div></div><div class="spec val" id="val-with_cache_rec"><a href="#val-with_cache_rec" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>with_cache_rec : ?⁠cb:(<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-callback">callback</a> <span class="keyword">‑></span> (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a> <span class="keyword">‑></span> ((<span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span>) <span class="keyword">‑></span> <span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span>) <span class="keyword">‑></span> <span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span></code></div><div class="doc"><p><code class="code">with_cache_rec c f</code> is a function that first, applies <code class="code">f</code> to
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some <code class="code">f' = fix f</code>, such that recursive calls to <code class="code">f'</code> are cached in <code class="code">c</code>.
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It is similar to <a href="index.html#val-with_cache">with_cache</a> but with a function that takes as
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first argument its own recursive version.
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Example (memoized Fibonacci function):
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</p><pre><code class="code"> let fib = with_cache_rec (lru 256)
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(fun fib' n -> match n with
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| 1 | 2 -> 1
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| _ -> fib' (n-1) + fib' (n-2)
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);;
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fib 70;;</code></pre><ul class="at-tag"><li><span class="at-tag parameter">Parameter</span> <span class="module-path">cb</span>: called after the value is generated or retrieved.</li></ul></div></div><div class="spec val" id="val-size"><a href="#val-size" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>size : (<span class="type-var">_</span>, <span class="type-var">_</span>) <a href="index.html#type-t">t</a> <span class="keyword">‑></span> int</code></div><div class="doc"><p>Size of the cache (number of entries). At most linear in the number
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of entries.</p></div></div><div class="spec val" id="val-iter"><a href="#val-iter" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>iter : (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a> <span class="keyword">‑></span> (<span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span> <span class="keyword">‑></span> unit) <span class="keyword">‑></span> unit</code></div><div class="doc"><p>Iterate on cached values. Should yield <code class="code">size cache</code> pairs.</p></div></div><div class="spec val" id="val-add"><a href="#val-add" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>add : (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a> <span class="keyword">‑></span> <span class="type-var">'a</span> <span class="keyword">‑></span> <span class="type-var">'b</span> <span class="keyword">‑></span> bool</code></div><div class="doc"><p>Manually add a cached value. Return <code class="code">true</code> if the value has successfully
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been added, and <code class="code">false</code> if the value was already bound.</p><ul class="at-tag"><li><span class="at-tag since">Since</span>: 1.5</li></ul></div></div><div class="spec val" id="val-dummy"><a href="#val-dummy" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>dummy : (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a></code></div><div class="doc"><p>Dummy cache, never stores any value.</p></div></div><div class="spec val" id="val-linear"><a href="#val-linear" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>linear : eq:<span class="type-var">'a</span> <a href="index.html#type-equal">equal</a> <span class="keyword">‑></span> int <span class="keyword">‑></span> (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a></code></div><div class="doc"><p>Linear cache with the given size. It stores key/value pairs in
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an array and does linear search at every call, so it should only be used
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with small size.</p><ul class="at-tag"><li><span class="at-tag parameter">Parameter</span> <span class="module-path">eq</span>: optional equality predicate for keys.</li></ul></div></div><div class="spec val" id="val-replacing"><a href="#val-replacing" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>replacing : eq:<span class="type-var">'a</span> <a href="index.html#type-equal">equal</a> <span class="keyword">‑></span> ?⁠hash:<span class="type-var">'a</span> <a href="index.html#type-hash">hash</a> <span class="keyword">‑></span> int <span class="keyword">‑></span> (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a></code></div><div class="doc"><p>Replacing cache of the given size. Equality and hash functions can be
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parametrized. It's a hash table that handles collisions by replacing
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the old value with the new (so a cache entry is evicted when another
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entry with the same hash (modulo size) is added).
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Never grows wider than the given size.</p></div></div><div class="spec val" id="val-lru"><a href="#val-lru" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>lru : eq:<span class="type-var">'a</span> <a href="index.html#type-equal">equal</a> <span class="keyword">‑></span> ?⁠hash:<span class="type-var">'a</span> <a href="index.html#type-hash">hash</a> <span class="keyword">‑></span> int <span class="keyword">‑></span> (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a></code></div><div class="doc"><p>LRU cache of the given size ("Least Recently Used": keys that have not been
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used recently are deleted first). Never grows wider than the given size.</p></div></div><div class="spec val" id="val-unbounded"><a href="#val-unbounded" class="anchor"></a><div class="def val"><code><span class="keyword">val </span>unbounded : eq:<span class="type-var">'a</span> <a href="index.html#type-equal">equal</a> <span class="keyword">‑></span> ?⁠hash:<span class="type-var">'a</span> <a href="index.html#type-hash">hash</a> <span class="keyword">‑></span> int <span class="keyword">‑></span> (<span class="type-var">'a</span>, <span class="type-var">'b</span>) <a href="index.html#type-t">t</a></code></div><div class="doc"><p>Unbounded cache, backed by a Hash table. Will grow forever
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unless <a href="index.html#val-clear">clear</a> is called manually.</p></div></div></body></html> |