TypeScript Typeclasses

This skill builds typeclass abstractions in TypeScript on Effect's higher-kinded type encoding. A typeclass — Functor, Monad, Traversable — is an interface abstracted over a type constructor (Array, Option, a custom Tree), not over a plain type. TypeScript cannot quantify over type constructors directly, so the abstraction is recovered through an encoding: a brand (Effect calls it a TypeLambda) names the constructor, and Kind applies it. The background and the theory live in references/hkt-encoding.md; this file is the workflow.

The work splits into four steps, preceded by a gate. Do not skip the gate — most requests for "HKTs" do not actually need them, and the encoding has a real cost.

Step 0 — Gate: are HKTs needed at all?

The encoding is a powerful tool with a standing cost: every call site that routes through Kind pays an inference-annotation tax and surfaces dense error messages (see references/troubleshooting.md). Adopt it only when it earns its place.