https://847850277.github.io/categories/f-function/ Recent content in F Function on ZhengPengDe Blog Hugo zh-CN Tue, 11 Aug 2026 18:00:00 +0000 https://847850277.github.io/posts/2026/datafusion_note_01/ Mon, 10 Aug 2026 09:00:00 +0000 https://847850277.github.io/posts/2026/datafusion_note_01/ <h1 id="datafusion-note">datafusion note</h1> <h2 id="a-computer-system-can-be-abstracted-as-a-function">A Computer System Can Be Abstracted as a Function</h2> <p>At the simplest level, a computer program can be modeled as a function:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-text" data-lang="text"><span style="display:flex;"><span>output = F(input) </span></span></code></pre></div><p>However, most real computer systems have state and depend on their environment. A more general model is:</p> <div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-text" data-lang="text"><span style="display:flex;"><span>(new state, output) = F(old state, input, environment) </span></span></code></pre></div><p>A software engineer’s job is to design, implement, and compose these state-transition functions.</p> <p>A large system can usually be decomposed into smaller functions:</p>