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Tolk Language: overview

Tolk is a new language for writing smart contracts in TON. Think of Tolk as the "next‑generation FunC". Tolk compiler is literally a fork of FunC compiler, introducing familiar syntax similar to TypeScript, but leaving all low-level optimizations untouched.

import "storage.tolk"

fun loadData() {
    ctxCounter = getContractData().beginParse().loadUint(32);
}

fun onInternalMessage(msgValue: int, msgFull: cell, msgBody: slice) {
    var cs = msgFull.beginParse();
    var flags = cs.loadMessageFlags();
    if (isMessageBounced(flags)) {
        return;
    }
    ...
}

get currentCounter(): int {
    loadData(); // fills global variables
    return ctxCounter;
}
See same logic implemented with FunC
#include "storage.fc";

() load_data() impure {
  slice cs = get_data().begin_parse();
  ctx_counter = cs~load_uint(32);
}

() recv_internal(int msg_value, cell msg_full, slice msg_body) impure {
  slice cs = msg_full.begin_parse();
  int flags = cs.load_uint(4);
  if (flags & 1) {
    return ();
  }
  ...
}

int currentCounter() method_id {
  load_data(); ;; fills global variables
  return ctx_counter;
}

Try a FunC → Tolk converter

Read "Tolk vs FunC differences"

Motivation behind Tolk​

FunC is awesome. It is really low-level and encourages a programmer to think about compiler internals. It gives full control over TVM assembler, allowing a programmer to make his contract as effective as possible. If you get used to it, you love it.

But there is a problem. FunC is "functional C", and it's for ninja. If you are keen on Lisp and Haskell, you'll be happy. But if you are a JavaScript / Go / Kotlin developer, its syntax is peculiar for you, leading to occasional mistakes. A struggle with syntax may decrease your motivation for digging into TON.

Imagine, what if there was a language, also smart, also low-level, but not functional and not like C? Leaving all beauty and complexity inside, what if it would be more similar to popular languages at first glance?

That's what Tolk is about.

Migrating from FunC to Tolk​

If you know FunC and want to try a new syntax, your way is:

  1. Read Tolk vs FunC: in short.
  2. With blueprint, create a new Tolk contract (for example, a counter) and experiment around. Remember, that almost all stdlib functions are renamed to verbose clear names. Here is a mapping.
  3. Try a converter for your existing contracts or one from FunC Contracts. Keep in mind that contracts written in Tolk from scratch would definitely look nicer than being auto-converted. For instance, using logical operators instead of bitwise tremendously increases code readability.

How to try Tolk if you don't know FunC​

Currently, this documentation assumes that you know FunC

The documentation describes "Tolk vs FunC" differences. Later it will be adapted to land newcomers. Moreover, FunC will eventually become deprecated, and all code snippets throughout the whole documentation will be rewritten to Tolk.

If you are new to TON, your way is:

  1. Dig into this documentation to acquire basic on development in TON. No matter what language you'll use, you need to be aware of cells, slices, TON asynchronous nature after all.
  2. Facing FunC snippets, you can still use FunC, or try to express the same in Tolk. If FunC syntax is peculiar for you, don't worry: the goal of Tolk is exactly to fix this issue.
  3. Once you gain some understanding of what's going on, try using Tolk with blueprint.

Tooling around Tolk Language​

Sources of the Tolk compiler are a part of the ton-blockchain repo. Besides the compiler, we have:

  1. tolk-js — a WASM wrapper for Tolk compiler.
  2. JetBrains IDE plugin supports Tolk besides FunC, Fift, TL/B, and Tact.
  3. VS Code Extension enabling Tolk Language support.
  4. Converter from FunC to Tolk — convert a .fc file to a .tolk file with a single npx command.
  5. Tolk Language is available in blueprint.

Is Tolk production-ready?​

The Tolk compiler, a fork of the FunC compiler, is deemed production-ready, albeit somewhat experimental at the moment.

Undiscovered bugs may exist, potentially inherited from FunC or attributable to TVM characteristics. Anyway, no matter what language you use, you should cover your contracts with tests to reach high reliability.

Roadmap​

The first released version of Tolk is v0.6, emphasizing missing FunC v0.5.

Here are some (yet not all and not ordered in any way) points to be investigated:

  • type system improvements: boolean type, nullability, dictionaries
  • structures, with auto-packing to/from cells, probably integrated with message handlers
  • structures with methods, probably generalized to cover built-in types
  • some integrations with TL scheme, either syntactical or via code generation
  • human-readable compiler errors
  • easier messages sending
  • better experience for common use-cases (jettons, nft, etc.)
  • gas and stack optimizations, AST inlining
  • extending and maintaining stdlib
  • think about some kind of ABI (how explorers "see" bytecode)
  • think about gas and fee management in general

Note, that most of the points above are a challenge to implement. At first, FunC kernel must be fully refactored to "interbreed" with abilities it was not designed for.

Also, I see Tolk evolution partially guided by community needs. It would be nice to talk to developers who have created interconnected FunC contracts, to absorb their pain points and discuss how things could be done differently.

Issues and Contacts​

If you face issue, connect to developer society on TON Dev Chats or create GitHub issues.