ReScript

ReScript is a statically-typed language that compiles to clean, readable, dependency-free ES modules — the emitted JS is meant to be reviewed and shipped, not treated as an artifact. Coming from JS/TS, the biggest mental shift is not syntax — it's that the type system is sound and always on: there is no any, no unknown-laundering, no strictNullChecks knob to forget in one project, and no structural escape hatch. The guarantees TypeScript makes opt-in are unconditional here.

Default to explaining why something is idiomatic, not just that it is — the user is learning the language, not just translating syntax.

The runtime story matters less than the type story: a record compiles to a JS array and a variant to a tagged block. The full value-representation walkthrough, and everything about talking to JavaScript: references/interop-and-runtime.md.

Type inference: don't annotate unless asked

ReScript infers every type globally with full soundness — not "best effort like TS but stricter". Unless the user asks for annotations or you're at a boundary, write bindings without any:

// Prefer
let totalTtc = (priceHt, taxRate) => priceHt * (1 + taxRate)

// Not, unless asked
let totalTtc = (priceHt: int, taxRate: int): int => priceHt * (1 + taxRate)