--- name: literate-programming-7c94cb9f1992 description: Use when creating new source files, writing new functions or types, or significantly rewriting existing code — ensures code is structured for humans to read first, with narrative preambles, reasoning-based documentation, and presentation ordered by understanding rather than compiler convention --- # Literate Programming ## Overview Don Knuth's core insight: **code is written for humans to read, and only incidentally for machines to execute.** This skill applies a pragmatic version of that principle — not Knuth's web/tangle toolchain, but the discipline of writing code whose structure and documentation make the reasoning visible to the next reader. Every file is a piece of writing, not just a collection of declarations. --- ## The Five Rules ### 1. Every file opens with a narrative preamble The preamble answers three questions: - **Why does this file exist?** What problem does it solve, and why is it the right place to solve it? - **What are the key design decisions?** Not a list of functions — the choices that shaped the structure. - **What does this file deliberately NOT do?** Explicit scope exclusions are as informative as inclusions. The preamble belongs in the package/module comment block, before any imports. It is prose, not bullet points. **Before (no preamble):** ```go package cache import ( "sync" "time" ) type Cache struct { ... } ``` **After (with preamble):** ```go // Package cache provides a short-lived, in-process store for rendered page // fragments. Its only job is to reduce redundant template execution on // repeated requests for the same URL within a single deploy. // // We deliberately avoid distributed caching (Redis, Memcached) here. The // fragments are cheap to recompute, the deploy cadence is high, and the // operational burden of a networked cache is not justified at current traffic. // If that changes, this package is the right place to swap the strategy. // // We do not attempt cache invalidation on content change — that problem // belongs to the deployment pipeline, not the request path. package cache ``` --- ### 2. Documentation explains reasoning, not signatures A comment that restates the function name or its parameter types adds no value. The code already shows WHAT. Documentation's job is to explain WHY — the design choice, the tradeoff, the constraint that shaped this particular approach. **Before (restates the signature):** ```go // getUserByID returns the user with the given ID from the database. func getUserByID(id string) (*User, error) { ``` **After (explains reasoning):** ```go // getUserByID loads from the read replica, not the primary. For the auth // hot-path this is acceptable because user records change rarely and a // replication lag of a few seconds is not observable by a human login flow. // Write operations that need immediate consistency call the primary directly. func getUserByID(id string) (*User, error) { ``` Apply the same standard to type definitions: explain why the type exists and what invariants it maintains, not just what its fields are. --- ### 3. Order of presentation follows logical understanding Arrange code so that a reader encounters concepts in the order they need them to build understanding — not in the order the compiler requires. This usually means: - **High-level orchestration before low-level detail.** The function that calls helpers should appear before the helpers, not after. - **Domain model before mechanics.** The type that represents the problem should appear before the functions that manipulate it. - **Purpose before implementation.** State what something is for before showing how it works. In Go and Kotlin this sometimes means forward references — that is fine. Readability for the human outweighs convention. --- ### 4. Each file has one clearly stated concern Name the file's single concern in the first sentence of the preamble. If you cannot state it in one sentence, the file has too many concerns and should be split. A file's concern is not its list of contents ("this file contains the parser, the renderer, and the helper functions"). It is its intellectual role ("this file transforms a flat markdown string into a navigable hierarchy of sections"). --- ### 5. Comments explain WHY, not WHAT Inline comments are for explaining decisions, constraints, and non-obvious consequences — not for narrating code that can speak for itself. | ❌ Describes WHAT | ✅ Explains WHY | | --- | --- | | `// increment counter` | `// counter is used by the rate limiter, not just for metrics` | | `// check if user is nil` | `// nil user is valid here — unauthenticated requests are allowed` | | `// loop over items` | `// process in reverse so removals don't shift the indices we haven't visited` | | `// return error` | `// surface the parse error; callers need the line number to show a useful message` | --- ## Quick Reference | Rule | Signal that it's missing | | --- | --- | | Narrative preamble | File opens directly with imports or a type declaration | | Reasoning-based docs | Function comment could be generated from the signature alone | | Logical order | Helper functions appear before the code that uses them | | Single stated concern | Preamble lists contents rather than naming the file's role | | WHY comments | Inline comment restates the next line in different words | --- ## Common Rationalizations | Rationalization | Reality | | --- | --- | | "The function name is self-explanatory" | Names say WHAT. Documentation explains WHY the design is this way, not another way. | | "I'll add documentation later" | Documentation written after implementation is biased toward describing what was built. LP documentation shapes what gets built. | | "The preamble would be too long" | A preamble proportional to the decisions made is never too long. A file with no decisions worth naming should not exist. | | "This is obvious" | Obvious to you now ≠ obvious to the next reader. Obvious things change; the reason they were obvious does not. | | "I'll write a docstring" | A docstring that restates the signature satisfies a tool, not a reader. | | "The code is the documentation" | The code shows the mechanism. LP documentation shows the reasoning. Both are needed. | ## Red Flags — Stop and Rewrite - File opens with `import` or a type/function declaration, no preamble - Any function comment that could be auto-generated from its signature - Helper functions defined before the code that calls them - A preamble that lists what the file contains rather than why it exists - An inline comment that starts with "this" and restates the next line --- Source attribution: Habitat-Thinking Original project: https://github.com/Habitat-Thinking/ai-literacy-superpowers/blob/a50b8136e8e170a828b7a61aa3e8815475b56bc9/ai-literacy-superpowers/skills/literate-programming/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. "Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. "You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. "Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. "Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. "Work" shall mean the work of authorship made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof. "Contribution" shall mean, as defined by Sections 1 through 9 of this document, any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works of the Work, that is intentionally submitted to the Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or designated in writing by the copyright owner as "Not a Contribution." "Contributor" shall mean Licensor and any Legal Entity on behalf of whom a Contribution has been received by the Licensor and subsequently incorporated within the Work. 2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form. 3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by the combined work of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or any Contribution embodied within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed. 4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions: (a) You must give any other recipients of the Work or Derivative Works a copy of this License; and (b) You must cause any modified files to carry prominent notices stating that You changed the files; and (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and (d) If the Work includes a "NOTICE" text file as part of its distribution, You must include a readable copy of the attribution notices contained within such NOTICE file, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or in addition to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License. You may add Your own license statement for Your modifications and may provide additional grant of rights to use, reproduce, modify, and distribute Your modifications, or for such Derivative Works as a whole, under terms and conditions that You define, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License. 5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions. 6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file. 7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or reproducing the Work and assume any risks associated with Your exercise of permissions under this License. 8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or exemplary damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may charge only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability. END OF TERMS AND CONDITIONS APPENDIX: How to apply the Apache License to your work. To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets "[]" replaced with your own identifying information. (Don't include the brackets!) The text should be enclosed in the appropriate comment syntax for the file format in use. It is also recommended that a file or directory "NOTICE" is included with your work that provides attribution notices that are separate from the LICENSE file. Copyright 2026 Russ Miles Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: Habitat-Thinking Original project: https://github.com/Habitat-Thinking/ai-literacy-superpowers/blob/a50b8136e8e170a828b7a61aa3e8815475b56bc9/ai-literacy-superpowers/skills/literate-programming/SKILL.md Attribution basis: Source repository record Fields of work: Content & Media, Development & Engineering, Product Management Roles: Backend Developer, Frontend Developer, Full-Stack Developer, Product Manager, Technical Writer Specialties: Backend, Cross Platform, Frontend Tools: Tool not specified Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 34f61e6424b147374837aa6120a8b6bfcf252efc38743c30488e42855d044af8