Type System

Advanced type system extensions: refined types, newtypes, HKT, phantom types, and type-level arithmetic.

Quick Start

npm install @typesugar/type-system

import { type Newtype, wrap, unwrap, type Refined, refine } from "@typesugar/type-system";

// Zero-cost branding
type UserId = Newtype<number, "UserId">;
const id = wrap<UserId>(42);

// Compile-time validated refinements
type Port = Refined<number, "Port">;
const port = refine<Port>(8080); // ✓
const bad = refine<Port>(-1); // ✗ Compile error

Features

Newtype — Zero-Cost Branding

Type-safe wrappers with zero runtime cost.

type Meters = Newtype<number, "Meters">;
type Feet = Newtype<number, "Feet">;

function calculateArea(width: Meters, height: Meters): number {
  return unwrap(width) * unwrap(height);
}

// Type-safe! Can't mix up Meters and Feet
calculateArea(wrap<Meters>(10), wrap<Feet>(5)); // Type error!

Refinement Types

Types with predicates validated at compile time for literals.

import { Positive, NonEmpty, Email, Port } from "@typesugar/type-system";

type ValidPort = Refined<number, typeof Port>;
const port = refine<Port>(8080); // ✓
const badPort = refine<Port>(-1); // ✗ Compile error

Higher-Kinded Types (HKT)

Type constructors as type parameters.

import { type $, type ArrayF, type PromiseF } from "@typesugar/type-system";

type Result = Kind<ArrayF, number>; // number[]
type Async = Kind<PromiseF, string>; // Promise<string>

Length-Indexed Arrays (Vec)

Arrays with compile-time known length.

import { Vec } from "@typesugar/type-system";

const v3: Vec<number, 3> = Vec.from([1, 2, 3]);
const first: number = Vec.head(v3); // ✓ Safe
const rest: Vec<number, 2> = Vec.tail(v3);

// Vec<T, 0> has no head — compile error!

Type-Level Arithmetic

import { Add, Mul, Pow } from "@typesugar/type-system";

type Sum = Add<1, 2>; // 3
type Product = Mul<4, 5>; // 20
type Power = Pow<2, 8>; // 256

Learn More

• API Reference
• Package README