Lykn

Fields and Private Members

Public Fields

(class Counter ()
  (field count 0)

  (increment ()
    (+= this:count 1)
    (return this:count)))

class Counter {
  count = 0;
  increment() {
    this.count += 1;
    return this.count;
  }
}

Private Members: The - Prefix

Lykn uses a naming convention that the compiler enforces at the JS engine level. A leading - on a name compiles to #_ — JavaScript’s private field syntax:

(class BankAccount ()
  (field -balance 0)

  (constructor (initial)
    (assign this:-balance initial))

  (deposit (amount)
    (+= this:-balance amount))

  (get balance ()
    (return this:-balance)))

class BankAccount {
  #_balance = 0;
  constructor(initial) {
    this.#_balance = initial;
  }
  deposit(amount) {
    this.#_balance += amount;
  }
  get balance() {
    return this.#_balance;
  }
}

-balance → #_balance. The developer writes a naming convention; the compiler produces engine-enforced privacy. No new syntax required — the - prefix is the entire mechanism.

Private methods work the same way:

(-validate (amount)
  (if (<= amount 0)
    (throw (new Error "Amount must be positive"))))

Compiles to #_validate(amount) { ... } — a private method, invisible outside the class.