Zero Cost Abstractions in Web Development

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2021-05-21 19:30:05

Constexpr is a feature found in statically compiled programming languages that allows evaluation of expressions in a program at compile time. Different languages have different terminology for it. For example, in zig lang, it's called comptime. Common lisp macros, in lisps that compile to native code, might also be grouped in this category.

This feature allows automatic generation of complex static data at compile time, and the runtime code can just use the result of compile time evaluated data. Variable inlining is a simple form of compile time evaluation. Ideally, the language/compiler should allow the users to turn any eligible piece of code "constexpr" with some annotations. The eligibility criteria being that the code must not depend on any runtime data.

constexpr.js is a tool that allows you to execute parts of javascript in your website before deployment. You can use it like a static site generator, as I do for this website. It's different from SSG's like Jakyll in that it doesn't force you to learn a dedicated domain specific language. There already exists a dedicated languages for dealing with DOM and webpages, javascript. With constexpr.js, you use javascript and usual DOM manipulation methods to generate the website. The whole browser runtime is available at your disposal when generating sites with constexpr.js.