Tact is a fresh programming language for TON Blockchain, focused on efficiency and ease of development. It is a good fit for complex smart contracts, quick onboarding and rapid prototyping. Tact is a statically typed language with a simple syntax and powerful type system.
What is Tact?
Familiar syntax
Tact offers familiar syntax inspired by JavaScript & Typescript, Swift, Kotlin and Rust. Powerful features such as algebraic data types and compile-time execution look organic and friendly to new developers.
receive("increment") {
self.val += 1;
}
get fun value(input: Int): Int {
return input + self.val;
}
Strong type system
Tact offers algebraic data types compatible with TL-B scheme. Arithmetic is always safe because integers have precise bounds. Tact compiler helps you perform necessary checks and does not produce silent failures or unexpected truncation.
struct ContractData {
index: Int as uint32;
admin: Address;
}
Gas control
Blockchain programs have strict execution cost model. Every operation must be paid for in real time and execution may fail mid-way if it runs out of gas.
Tact makes cross-contract messages safe with precise gas commitments and compiler checks of the execution costs. Variable costs are either statically bounded, or checked explicitly in runtime.
receive("sample message") {
require(context().value >= ton("0.1"), "must pay at least 0.1 TON");
// (....etc) //
}
Secure and robust
Tact compiler version 1.5.0 has passed a security review by Trail of Bits with no high-severity vulnerabilities found. See the full PDF report.
If the previous link didn't work, try this one with a copy of the report distributed from our website: PDF report.
Tact and FunC
FunC is a lower-level language aimed at developers who are deeply familiar with TON architecture. FunC liberates developers from writing raw Fift code, while providing the same level of control.
Unfortunately, the precision of FunC makes it harder to write complex multi-contract systems.
Tact enables developers to go even further: you can write the entire suites of smart contracts with strongly typed interfaces and statically verified execution costs. With Tact you can focus on your problem and worry less about blockchain idiosyncrasies.
Bright future awaits
Tact is developed in the open source and open development model on GitHub — suggestions, issues and bug fixes are welcome. In addition, GitHub provides syntax highlighting for Tact code across the website.
Many Tact contracts have already been written and more and more projects are using Tact in production.
In addition, Trail of Bits, one of the leading Web3 security firms, has made a security audit of Tact v1.5 and found zero high-severity vulnerabilities. See the full PDF report.
To start writing ⚡ Tact yourself, see the Let's start section on the main page of the Tact Docs. Good luck on your coding adventure!