Essence

A programming language, with a focus on essential language features and simplicity.

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Project maintained by alexandertrefz Hosted on GitHub Pages — Theme by mattgraham

Goals

The main goal for Essence is to allow the authoring of bug-free maintainable code, in a fast and pleasant manner. Essence features a strong type system combined with a mixture of functional and object oriented concepts, enabling code that is easy to understand & maintain.

Its syntax and features are designed with modern IDE’s in mind, allowing for great code completion & inline documentation features.

Essence compiles to modern ECMAScript, allowing execution in Bun, Node.js as well as browsers.

The Essence

• Explicit is better than implicit.
• Extensibility is better than completeness.
• Creating correct code must be enjoyable.
• Prototyping must be fast – thus refactoring must be painless.
• Readability counts.
• There should be one – and preferably only one – obvious way to do it.
• Practicality beats purity.
• Simple is better than complex.
• Complex is better than complicated.
• Beautiful is better than ugly.
• Clever is seldom good.

Features

• All Data is Immutable
• Static Structural Typing
• Type Inference
• Compact & Readable Syntax
• Algebraic Data Types
• Modules
• Protocols
• Generics
• Named Parameters
• Arbitrary Precision Numbers
• First-Class Functions

Example Code

You can find the most recent and working example of syntax in the HelloWorld.es as well as the other files in packages/fixtures/files. It also should be noted that the syntax is meant to be viewed with a font with code ligatures, like FiraCode.

You can compile any of them with the essence executable in packages/cli/bin. This produces a self-contained ES module of the same name beside the source — the parts of the runtime the program actually uses are bundled in, so it runs under Bun or Node, or in a browser, with nothing else installed.

essence HelloWorld.es       # compile to HelloWorld.js
essence run HelloWorld.es   # compile and execute in one step
essence check *.es          # type-check only, no output
essence format *.es         # format in place

That one executable carries the whole toolchain — build, run, check, watch, format and lsp — and essence help describes every command. The older names still work as aliases: esc is essence, esfmt is essence format, and esls is essence lsp.

The current runtime implementation is rudimentary however. There are many features missing from the standard library. Various langauge features are only partially implemented.

Disclaimer

This language is still a work in progress. It is not ready for use yet and there is no documentation as most things are in flux. Generally: Here be dragons!