Core Language

type

Generates TypeScript type definitions with typed fields.

type name=User
  field name=id type=string
  field name=email type=string
  field name=role type="admin|editor|viewer"
  field name=createdAt type=Date

export type User = {
  id: string;
  email: string;
  role: 'admin' | 'editor' | 'viewer';
  createdAt: Date;
};

interface

Generates TypeScript interfaces with method signatures.

interface name=AuthService
  fn name=login params="email:string,password:string" returns="Promise<User>"
  fn name=logout returns=void
  fn name=getSession returns="Promise<Session|null>"

export interface AuthService {
  login(email: string, password: string): Promise<User>;
  logout(): void;
  getSession(): Promise<Session | null>;
}

fn

Standalone function declarations. Can be children of interface or standalone.

fn name=calculateTotal params="items:CartItem[]" returns=number

machine

State machines with typed transitions. 12 lines of KERN generate 140+ lines of TypeScript: enum, type guards, transition function, exhaustive checks.

machine name=OrderStatus initial=pending
  transition from=pending to=confirmed event=confirm
  transition from=confirmed to=processing event=process
  transition from=processing to=shipped event=ship
  transition from=shipped to=delivered event=deliver
  transition from=pending to=cancelled event=cancel
  transition from=confirmed to=cancelled event=cancel

• enum OrderStatusState with all states
• enum OrderStatusEvent with all events
• Type guard functions (isPending, isConfirmed, ...)
• Typed transition function with exhaustive switch
• State machine class with current state tracking

event

Event type declarations for event-driven architectures.

event name=UserCreated
event name=UserDeleted
event name=OrderPlaced

config

Configuration objects with typed fields.

config name=AppConfig
  field name=apiUrl type=string
  field name=debug type=boolean
  field name=maxRetries type=number

store

State store declarations.

store name=AuthStore
  field name=user type="User|null"
  field name=token type=string
  field name=isLoading type=boolean

error

Custom error type declarations.

error name=ValidationError
error name=NotFoundError
error name=AuthenticationError

module

Module declarations for organizing exports.

module name=auth
  export name=AuthService
  export name=User
  export name=Session

test

Test declarations with describe/it structure.

test name=AuthTests
  describe name=login
    it name="authenticates valid user"
    it name="rejects invalid password"
  describe name=logout
    it name="clears session"