Tolk is a statically typed language for writing smart contracts on TON. It provides declarative data structures, automatic cell serialization, and message handling primitives. The language compiles to TVM and provides direct control over execution. 
type AllowedMessage = CounterIncrement | CounterReset

contract Counter {
    storage: Storage
    incomingMessages: AllowedMessage
}

fun onInternalMessage(in: InMessage) {
    val msg = lazy AllowedMessage.fromSlice(in.body);
    match (msg) {
        CounterIncrement => { ... }
        CounterReset => { ... }
    }
}

get fun currentCounter() {
    val storage = lazy Storage.load();
    return storage.counter;
}
Tolk is compatible with existing TON standards.

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Key features

Tolk provides high-level readability while preserving low-level control:
  • a type system for describing cell layouts;
  • lazy loading that skips unused fields;
  • unified message composition and deployment;
  • a contract declaration that drives ABI export, TypeScript wrappers, source maps, and debugging;
  • a compiler targeting the Fift assembler;
  • tooling with IDE integration.

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From FunC to Tolk

Tolk evolved from FunC and is now the recommended language for TON smart contracts. To migrate from FunC:

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Quick start

Follow the quickstart page in the Acton documentation.

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IDE support

  1. JetBrains IDEs plugin provides syntax highlighting and code navigation.
  2. VSCode extension adds syntax highlighting, code navigation, and other language features for VS Code and VS Code-based editors such as VSCodium, Cursor, and Windsurf.
  3. Language server supports (Neo)Vim, Helix, and other editors with LSP support.

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