New project announcement
I shipped skillcraft.ai - a tool that helps you find the best learning resources tailored to your goals. All you need to do is tell it what you want to learn, and I’ll find the right resources to get you there.
Up to date
Published
4 min read

Trevor I. Lasn

Building tools for developers. Currently building skillcraft.ai and blamesteve.lol

Explicit is better than implicit

Clarity is key: being explicit makes your code more readable and maintainable.

I’m convinced that implicitness leads to a higher WTF per Minute (WTFPM) in the long run.

WTF per Minute

Implicitness requires the coder to remember hidden details instead of having them clearly defined in the code. For example, can you tell me why we’re adding “10” here?

JavaScript
// Implicit (bad)
function calculateSalary(a, b) {
return a + b + 10; // a?? b?? WTF is 10?
}

Exactly, that was the point. No one can tell what “10” represents except the person who wrote it, and that’s awful in my opinion. If you have a team of engineers working on a project, how can anyone possibly navigate the codebase with such ambiguity?

Instead of implicitly adding “10”, we can prevent future headaches by simply creating a clear variable for the bonus. In my view, relying too heavily on implicit behavior can cause confusion and make managing the codebase more difficult.

JavaScript
// Explicit (good)
function calculateSalary(cash, equity) {
const bonus = 10; // Explicit bonus variable
return cash + equity + bonus;
}

Tim Peters’ second point in The Zen of Python states, “Explicit is better than implicit,” and I couldn’t agree more.

Imagine a function that grants access to different parts of a system based on a user’s role. In this example, implicit behavior leads to confusion about which roles have which permissions, making the code difficult to maintain.

JavaScript
// Implicit (bad)
function grantAccess(user) {
if (user.role === 'admin') {
return ['read', 'write', 'delete']; // Full access
}
if (user.role === 'editor') {
return ['read', 'write']; // Editors can't delete
}
if (user.role === 'viewer') {
return ['read']; // View-only access
}
// Implicit fallback
return ['none']; // WTF is 'none'?
}
function showAccessControls(user) {
const permissions = grantAccess(user);
if (permissions.includes('read')) {
console.log("User has read access.");
}
if (permissions.includes('write')) {
console.log("User has write access.");
}
if (permissions.includes('delete')) {
console.log("User has delete access.");
}
}
// Example usage
const user1 = { name: "Alice", role: "admin" };
const user2 = { name: "Bob", role: "viewer" };
const user3 = { name: "Charlie", role: "guest" }; // Implicit 'none' fallback
showAccessControls(user1); // Has all access
showAccessControls(user2); // Read-only access
showAccessControls(user3); // No access, but why?

The access control is handled with hard-coded roles and magic strings like ‘none’, making it unclear and unmanageable as more roles are added. Permissions are scattered throughout the code, leading to confusion and maintenance issues for future developers.

JavaScript
// Explicit (good)
const ROLE_PERMISSIONS = {
admin: ['read', 'write', 'delete'],
editor: ['read', 'write'],
viewer: ['read'],
guest: [] // Explicitly defining guest permissions
};
function grantAccess(user) {
const permissions = ROLE_PERMISSIONS[user.role] || ROLE_PERMISSIONS['guest'];
return permissions;
}
function showAccessControls(user) {
const permissions = grantAccess(user);
if (permissions.includes('read')) {
console.log(`${user.name} has read access.`);
}
if (permissions.includes('write')) {
console.log(`${user.name} has write access.`);
}
if (permissions.includes('delete')) {
console.log(`${user.name} has delete access.`);
}
if (permissions.length === 0) {
console.log(`${user.name} has no access.`);
}
}
// Example usage
const user1 = { name: 'Alice', role: 'admin' };
const user2 = { name: 'Bob', role: 'viewer' };
const user3 = { name: 'Charlie', role: 'guest' };
showAccessControls(user1); // Alice has read, write, and delete access.
showAccessControls(user2); // Bob has read access.
showAccessControls(user3); // Charlie has no access.

Why Explicit is Better

  • Explicit Mapping: The ROLE_PERMISSIONS object clearly defines each role and its corresponding permissions.

  • Clarity: By making permissions explicit, there’s no need for magic strings or conditionals scattered across the codebase.

  • Maintainability: Future roles or changes to permissions can be easily updated in one place.

In my opinion, “Explicit is better than implicit” is about choosing clear, direct code over concise but potentially ambiguous alternatives. This principle puts readability and maintainability first, even if it means writing slightly more verbose code.

By being explicit, the intentions behind the code are obvious, making it easier for any developer to understand and work with the codebase.


Found this article helpful? You might enjoy my free newsletter. I share dev tips and insights to help you grow your coding skills and advance your tech career.


Check out these related articles that might be useful for you. They cover similar topics and provide additional insights.

Webdev
6 min read

Inside the CSS Engine: CSSOM Explained

A deep dive into how browsers parse and manipulate CSS, its impact on web performance, and why it matters

Oct 25, 2024
Read article
Webdev
4 min read

Optimize Your Astro Site's <head> with astro-capo

Automatically improve your Astro site's performance using astro-capo

Oct 19, 2024
Read article
Webdev
4 min read

LH and RLH: The CSS Units That Make Vertical Spacing Easy

Exploring new CSS line-height units that eliminate guesswork from vertical rhythm

Dec 3, 2024
Read article
Webdev
8 min read

Become a Web Developer in 180 Days

A comprehensive roadmap to becoming a proficient web developer

Oct 29, 2019
Read article
Webdev
3 min read

NPQ: Open source CLI tool that audits and protects your npm installs from malicious packages

A CLI tool that checks packages for security issues and social engineering attacks before they hit your project

Jul 26, 2025
Read article
Webdev
12 min read

Robust Data Fetching Architecture For Complex React/Next.js Apps

How I use the 'Three Layers of Data' architecture pattern for React and Next.js apps to avoid common pitfalls, tech debt, and improve performance

May 4, 2025
Read article
Webdev
4 min read

Mental Toughness is the Best Quality a Developer Can Have

Mental toughness gets developers through challenges like debugging, picking up new tools, and hitting tight deadlines. It’s about staying calm and pushing through when things get tough.

Sep 12, 2024
Read article
Webdev
3 min read

Form Validation That Doesn't Annoy Users: CSS :user-valid and :user-invalid

The new pseudo-classes :user-valid and :user-invalid give us a smarter way to style form validation states based on user interaction

Dec 12, 2024
Read article
Webdev
3 min read

CSS :has() - The Parent Selector We've Always Wanted

Transform your CSS with :has(), the game-changing selector that finally lets us style elements based on their children.

Dec 4, 2024
Read article

This article was originally published on https://www.trevorlasn.com/blog/explicit-is-better-than-implicit. It was written by a human and polished using grammar tools for clarity.