What's coming in Super.js 0.2.0

v0.1.0 shipped the core language — null safety, sum types, match expressions, and the VS Code extension. Here's a preview of what v0.2.0 will focus on.

Stricter banned-feature enforcement

v0.2.0 will emit errors for all banned TypeScript features at the parser level rather than only in the type checker:

• any → use dynamic or unknown
• A & B intersection types → use interface extends
• T extends U ? X : Y conditional types
• { [P in keyof T]: ... } mapped types
• enum → use sum types or string unions

// SJS-E004 in v0.2.0 — caught at parse time
let x: any = 5         // error

// Fix
let x: dynamic = legacyLib.getValue()
if (typeof x === "number") {
  const n: number = x
}

Improved error messages

Every diagnostic will link to its spec/error-codes/SJS-EXXX.md page and include a one-line fix suggestion. superjs explain SJS-E001 will print the full explanation and example fixes.

dynamic propagation warnings

In --strict mode, SJS-W001 will fire whenever a dynamic value flows into typed code without narrowing:

const raw: dynamic = fetchJson()
console.log(raw.name)            // SJS-W001 in strict mode — narrow first

// Fix
if (typeof raw === "object" && raw !== null) {
  console.log((raw as { name: string }).name)
}

What's next

See the full roadmap for the Stage 0–6 plan.