Validation

Zero-cost validation and schema macros. Compile-time type guards, assertions, and validation with rich error accumulation.

Quick Start

npm install @typesugar/validate

import { is, assert, validate } from "@typesugar/validate";

interface User {
  name: string;
  age: number;
  email?: string;
}

const isUser = is<User>();

if (isUser(data)) {
  console.log(data.name); // data is typed as User
}

Features

Type Guards

Generate type guards at compile time:

const isUser = is<User>();

if (isUser(data)) {
  // data is typed as User
  console.log(data.name);
}

Assertions

Assert and narrow types with runtime checks:

const assertUser = assert<User>();

const user = assertUser(data); // throws if invalid
console.log(user.name); // user is typed as User

Validation with Error Accumulation

Collect all validation errors instead of failing fast:

const validateUser = validate<User>();

const result = validateUser(data);
result.fold(
  (errors) => console.error("Validation failed:", errors),
  (user) => console.log("Valid user:", user.name)
);

Schema DSL

Build schemas programmatically:

import { Schema } from "@typesugar/validate";

const UserSchema = Schema.object({
  name: Schema.string().minLength(1),
  age: Schema.number().int().min(0).max(150),
  email: Schema.string().email().optional(),
});

const result = UserSchema.validate(data);

Zero-Cost

All validation logic is generated at compile time:

// Generated code for is<User>()
function isUser(value: unknown): value is User {
  return (
    typeof value === "object" &&
    value !== null &&
    typeof (value as any).name === "string" &&
    typeof (value as any).age === "number"
  );
}

Learn More

• API Reference
• Package README