https://nalar.dev/tags/io.reader/ Recent content in Io.Reader on Nalar Hugo en-us Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/reading-streams-correctly-in-go-with-io-reader/ Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/reading-streams-correctly-in-go-with-io-reader/ <p>Go&rsquo;s <code>io.Reader</code> interface is tiny:</p> <div x-data="{ code: $el.querySelector('code').innerText, copied: false }" class="code-block group relative my-6 overflow-hidden rounded-xl border border-line bg-surface-muted dark:border-night-line dark:bg-night-surface"> <button type="button" @click="navigator.clipboard.writeText(code); copied = true; setTimeout(() => copied = false, 1600)" class="absolute right-3 top-3 z-10 rounded-lg border border-line-strong bg-surface px-2 py-1 font-mono text-[0.65rem] text-muted opacity-0 transition group-hover:opacity-100 hover:bg-ink hover:text-white dark:border-night-line dark:bg-night dark:text-night-muted dark:hover:bg-white dark:hover:text-ink"> <span x-text="copied ? 'Copied' : 'Copy'"></span> </button> <div class="overflow-x-auto p-4 text-sm leading-6 [&_pre]:!m-0 [&_pre]:!bg-transparent [&_pre]:!p-0 [&_code]:font-mono"> <div class="highlight"><pre tabindex="0" style="background-color:#fff;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-go" data-lang="go"><span style="display:flex;"><span><span style="font-weight:bold">type</span> Reader <span style="font-weight:bold">interface</span> { </span></span><span style="display:flex;"><span> Read(p []<span style="">byte</span>) (n <span style="">int</span>, err <span style="">error</span>) </span></span><span style="display:flex;"><span>}</span></span></code></pre></div> </div> </div> <p>Its small surface hides an important contract: a read is allowed to return fewer bytes than the buffer can hold, and it can return useful bytes together with an error. Correct stream processing must handle both cases.</p>