69 lines
3.8 KiB
Markdown
69 lines
3.8 KiB
Markdown
---
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layout: default
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title: "Thunks"
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parent: Abstraction
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ancestor: Funcons-beta
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---
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[Funcons-beta] : [Thunks.cbs]
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-----------------------------
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### Thunks
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<div class="highlighter-rouge"><pre class="highlight"><code>[
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<i class="keyword">Datatype</i> <span class="name"><a href="#Name_thunks">thunks</a></span>
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<i class="keyword">Funcon</i> <span class="name"><a href="#Name_thunk">thunk</a></span>
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<i class="keyword">Funcon</i> <span class="name"><a href="#Name_force">force</a></span>
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]</code></pre></div>
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<div class="highlighter-rouge"><pre class="highlight"><code><i class="keyword">Meta-variables</i>
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<span id="PartVariable_T"><i class="var">T</i></span> <: <span class="name"><a href="../../Value-Types/index.html#Name_values">values</a></span></code></pre></div>
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<div class="highlighter-rouge"><pre class="highlight"><code><i class="keyword">Datatype</i>
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<span class="name"><span id="Name_thunks">thunks</span></span>(<span id="Variable40_T"><i class="var">T</i></span>) ::= <span id="Name_thunk">thunk</span>(_:<span class="name"><a href="../Generic/index.html#Name_abstractions">abstractions</a></span>(()=><span id="Variable62_T"><i class="var">T</i></span>))</code></pre></div>
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<code><span class="name"><a href="#Name_thunks">thunks</a></span>(<i class="var">T</i>)</code> consists of abstractions whose bodies do not depend on
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a given value, and whose executions normally compute values of type <code><i class="var">T</i></code>.
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<code><span class="name"><a href="#Name_thunk">thunk</a></span>(<span class="name"><a href="../Generic/index.html#Name_abstraction">abstraction</a></span>(<i class="var">X</i>))</code> evaluates to a thunk with dynamic bindings,
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<code><span class="name"><a href="#Name_thunk">thunk</a></span>(<span class="name"><a href="../Generic/index.html#Name_closure">closure</a></span>(<i class="var">X</i>))</code> computes a thunk with static bindings.
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<div class="highlighter-rouge"><pre class="highlight"><code><i class="keyword">Funcon</i>
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<span class="name"><span id="Name_force">force</span></span>(_:<span class="name"><a href="#Name_thunks">thunks</a></span>(<span id="Variable187_T"><i class="var">T</i></span>)) : =><span id="Variable207_T"><i class="var">T</i></span></code></pre></div>
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<code><span class="name"><a href="#Name_force">force</a></span>(<i class="var">H</i>)</code> enacts the abstraction of the thunk <code><i class="var">H</i></code>.
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<div class="highlighter-rouge"><pre class="highlight"><code><i class="keyword">Rule</i>
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<span class="name"><a href="#Name_force">force</a></span>(<span class="name"><a href="#Name_thunk">thunk</a></span>(<span class="name"><a href="../Generic/index.html#Name_abstraction">abstraction</a></span>(<span id="Variable257_X"><i class="var">X</i></span>))) ~> <span class="name"><a href="../../../Computations/Normal/Giving/index.html#Name_no-given">no-given</a></span>(<a href="#Variable257_X"><i class="var">X</i></a>)</code></pre></div>
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____
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From the [PLanCompS Project] | [CBS-beta issues...] | [Suggest an improvement...]
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[Thunks.cbs]: Thunks.cbs
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"CBS SOURCE FILE"
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[Funcons-beta]: /CBS-beta/docs/Funcons-beta
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"FUNCONS-BETA"
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[Unstable-Funcons-beta]: /CBS-beta/docs/Unstable-Funcons-beta
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"UNSTABLE-FUNCONS-BETA"
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[Languages-beta]: /CBS-beta/docs/Languages-beta
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"LANGUAGES-BETA"
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[Unstable-Languages-beta]: /CBS-beta/docs/Unstable-Languages-beta
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"UNSTABLE-LANGUAGES-BETA"
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[CBS-beta]: /CBS-beta "CBS-BETA"
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[PLanCompS Project]: https://plancomps.github.io
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"PROGRAMMING LANGUAGE COMPONENTS AND SPECIFICATIONS PROJECT HOME PAGE"
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[CBS-beta issues...]: https://github.com/plancomps/CBS-beta/issues
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"CBS-BETA ISSUE REPORTS ON GITHUB"
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[Suggest an improvement...]: mailto:plancomps@gmail.com?Subject=CBS-beta%20-%20comment&Body=Re%3A%20CBS-beta%20specification%20at%20Values/Abstraction/Thunks/Thunks.cbs%0A%0AComment/Query/Issue/Suggestion%3A%0A%0A%0ASignature%3A%0A
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"GENERATE AN EMAIL TEMPLATE"
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