Civet: A Superset of TypeScript

Original Article ↗ Hacker News Discussion ↗

What Civet Is Trying to Be

  • Superset of TypeScript that adds new syntax and quickly adopts TC39 proposals.
  • Aims to be a playground for JS/TS language ideas while preserving TS tooling and allowing “eject” back to TS.
  • Claims most features are optional; plain TS should compile as-is.

Comparisons to CoffeeScript and Prior “Guest Languages”

  • Many see Civet as “CoffeeScript for TypeScript” (including the name pun).
  • Some praise CoffeeScript’s historical role in pushing JS forward (arrow functions, destructuring, classes, etc.) and hope Civet can do the same as a de‑facto research language.
  • Others recall CoffeeScript migrations as painful, calling it a dead end that made JS quirks harder to reason about and encouraged footguns.
  • Concern that guest languages tend to diverge from their host ecosystems unless they become platforms of their own.

Syntax, Readability, and Ergonomics

  • Fans like: significant indentation, “everything is an expression”, pipe operators, pattern matching, JSX improvements, list/for comprehensions, dedented multiline strings.
  • Critics see the syntax as too terse, “write‑only”, and optimized for typing speed over readability and long‑term maintenance.
  • Particular controversy over:
    • Optional parentheses and brackets.
    • Implicit returns plus “everything is an expression”.
    • Custom infix operators like value min ceiling max floor.
  • Some like indentation-based syntax (Python/YAML/GDScript parallels); others strongly prefer explicit braces for clarity and tooling (selecting scopes, avoiding subtle bugs).

Types, Tooling, and Runtime Semantics

  • Civet relies on TS for type checking; authors argue types mitigate some CoffeeScript-style pitfalls (implicit returns, terse pipelines).
  • Tooling: VS Code, bundlers, ESLint plugins exist but are acknowledged as imperfect.
  • Debugging/transpilation: source maps are assumed; some worry about performance or semantic gaps when building another layer atop TS.

Adoption, Risk, and Use Cases

  • Enthusiasts see Civet as great for personal projects, fast experimentation, or trying out future JS/TS features early.
  • Many commenters would not adopt it in production or team settings due to added cognitive load, inconsistent styles, and migration risk if proposals evolve or are rejected.
  • Some argue JS/TS should instead gain a few key features directly (pattern matching, pipelines, comprehensions, better type ergonomics) rather than spawning new surface syntaxes.