Lykn

Deno: Linting and Formatting

Deno includes a linter (deno lint) and a formatter (deno fmt) built in. No external tools needed, no configuration files, no plugins to install.

Linting

deno lint dist/              # lint compiled JS output
deno lint src/               # lint JS source (if any)

Deno’s linter uses recommended rules by default. It catches common JavaScript issues — unused variables, implicit type coercion, unreachable code.

Formatting

deno fmt dist/               # format compiled output
deno fmt --check dist/       # check without modifying (CI mode)

Deno’s formatter is opinionated — consistent indentation, semicolons, quote style. Like Prettier, but built in.

Lykn-Specific Considerations

The == null exception: Lykn’s some-> and compiler-generated null checks use == null (loose equality). Deno’s no-explicit-any and equality rules may flag these. Configure exceptions in project.json if needed:

{
  "lint": {
    "rules": {
      "exclude": ["no-explicit-any"]
    }
  }
}

Generated code patterns: The compiled JS is generated output. Some lint rules may flag patterns from match IIFEs or gensym variable names. These are correct code — suppress or exclude generated directories as needed.

Why Not a Separate Linter?

Deno’s built-in tools align with Lykn’s philosophy: fewer tools, fewer config files, fewer things that can go wrong. The lykn project itself uses deno lint — no Biome, no ESLint, no external dependencies. One runtime does it all.