index.html

<!DOCTYPE html>
<html>
    <head>
      <!-- SPDX-FileCopyrightText: 2025 Arthur A. Gleckler -->
      <!-- SPDX-License-Identifier: MIT -->
      <title>Pipeline Operators</title>
      <link href="/admin.css" rel="stylesheet">
      <link href="/list.css" rel="stylesheet">
      <link href="/favicon.png" rel="icon" sizes="192x192" type="image/png">
      <meta charset="utf-8">
      <meta name="viewport" content="width=device-width, initial-scale=1">
      <script type="text/x-mathjax-config">MathJax.Hub.Config({tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']]}});</script>
      <script crossorigin="anonymous" integrity="sha384-Ra6zh6uYMmH5ydwCqqMoykyf1T/+ZcnOQfFPhDrp2kI4OIxadnhsvvA2vv9A7xYv" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML" type="text/javascript"></script></head>
    <body>
      <h1>SRFI 197: Pipeline Operators</h1>
      <p class="authors">by Adam Nelson</p>
      <p class="based-on"></p>
      <p class="status">status: <em>final</em> (2020-09-12)</p>
      <p class="keywords">keywords: <a href="https://srfi.schemers.org/?keywords=syntax">Syntax</a></p>
      <ul class="info">
        <li><a href="srfi-197.html">The SRFI Document</a></li>
        <li><a href="https://srfi-email.schemers.org/srfi-197/">Discussion Archive</a></li>
        <li><a href="https://github.com/scheme-requests-for-implementation/srfi-197">Git repo (on GitHub)</a></li>
        <li><a href="mailto:srfi-197@srfi.schemers.org">srfi-197@<span class="antispam">nospam</span>srfi.schemers.org (subscribers only)</a></li>
        <li><span class="firefox-column-workaround">
            <form method="POST" action="https://www.simplelists.com/subscribe.php">
              <div class="title">Subscribe to srfi-197 mailing list</div><input name="email" placeholder="email address" tabindex="1" type="email"><input name="name" placeholder="full name" tabindex="2" type="text">
              <p><input id="sub-digest" name="digest" tabindex="3" type="checkbox" value="digest"><label for="sub-digest">daily digest?</label></p><input class="submit" name="submit" tabindex="4" type="submit" value="Subscribe to srfi-197"><input type="hidden" name="action" value="subscribe"><input type="hidden" name="list" value="srfi-197@srfi.schemers.org"></form></span></li>
        <li><span class="firefox-column-workaround">
            <form method="POST" action="https://www.simplelists.com/subscribe.php">
              <div class="title">Unsubscribe from srfi-197 mailing list</div><input name="email" placeholder="email address" tabindex="5" type="email"><input class="submit" name="submit" tabindex="6" type="submit" value="Unsubscribe from srfi-197"><input type="hidden" name="action" value="unsubscribe"><input name="list" type="hidden" value="srfi-197@srfi.schemers.org"></form></span></li></ul>
      <h2>Abstract</h2><p>Many functional languages provide pipeline operators, like Clojure's <code>-&gt;</code> or OCaml's <code>|&gt;</code>. Pipelines are a simple, terse, and readable way to write deeply-nested expressions. This SRFI defines a family of <code>chain</code> and <code>nest</code> pipeline operators, which can rewrite nested expressions like <code>(a b (c d (e f g)))</code> as a sequence of operations: <code>(chain g (e f _) (c d _) (a b _))</code>.</p></body></html>