How to migrate smart contracts from Ethereum’s Solidity to Soroban Rust

In this tutorial, we'll explore the intricacies of two major smart contract programming environments: Ethereum's Solidity and Soroban’s Rust SDK and why you should consider migrating your smart contracts to Rust.

In the blockchain and smart contract realm, Rust is a standout choice for developers, and here's why:

• Speed & Efficiency: Rust whizzes through tasks like a sports car in style. It is super fast, even outpacing C++ when it comes to speed and efficiency so that your blockchain operations are not just quick but also saves on computing resources.
• Type Safety: Picture Rust's type system as a meticulous inspector, who is watching each bit of your code at compile time. This means fewer errors and a safer environment for your smart contracts.
• Memory Safety Without the Overhead: Rust boasts top-shelf memory safety, acting as an invisible shield against vulnerabilities critical in the blockchain world. And it does this leanly without needing a garbage collector, keeping your projects lean and fortified.
• Conquering Concurrency with Ease: In blockchain, handling simultaneous transactions is like juggling fireballs. Rust excels in managing multiple operations seamlessly, preventing the common complications seen in other languages. This leads to faster, safer processing of transactions, enhancing the overall performance of your smart contracts.

Rust combines speed, safety, and execution efficiency making it an ideal language for blockchain development where such qualities are demanded. So how does Rust stack up against Solidity?

Open the remix-ide in your browser by navigating to: remix.ethereum.org/

Click on the “create new file” icon in the "File Explorer" tab.

Type the file name “HelloWorld.sol” and enter the following code into the ide:

```

// SPDX-License-Identifier: MIT

// compiler version must be greater than or equal to 0.8.20 and less than 0.9.0

pragma solidity >=0.7.0 <0.9.0;




contract HelloWorld {

function hello(string memory to) public pure returns(string memory){

string memory greeting = string(abi.encodePacked("hello ", to));

return greeting;

}

}

```

Once the code is in Remix, click the "Solidity Compiler" icon below the “File Explorer” icon.

Then, click “Compile HelloWorld.sol” or simply press `cmd+s`

Once compiled successfully click the icon below “Solidity Compiler” that is “Deploy & Run Transactions”.

Without changing any of the values as shown above just click the “Deploy” button to deploy your smart contract. Once deployed you will find your smart contract just below in “Deployed Contracts” heading.

Click “>” before your contract you will see a button “hello” below as our contract has a hello function variable that returns a string composed of “hello” + the value you passed in for the `to` argument.

Define an value for to and then click the “hello” button to return the greeting.

Nicely done! Now for the real Mccoy!

```
#![no_std]
```

This directive is used at the beginning of the Rust code to specify that the standard library (std) should not be included in the build. In Soroban contracts, the standard library is excluded because it's large and not suitable for deployment on blockchains.

```
use soroban_sdk::{contract, contractimpl, symbol_short, vec, Env, Symbol, Vec};
```

• The **use** keyword is used to import external dependencies or modules into the current Rust code.
• **soroban_sdk**: This is the crate/module that provides the necessary functionalities and types for Soroban contracts.
• **{contract, contractimpl, symbol_short, vec, Env, Symbol, Vec}**: These are the specific items being imported from the **soroban_sdk** module, including attributes, macros **(contract, contractimpl, symbol_short!)**, and data types **(Env, Symbol, Vec)**.

```
#[contract]
pub struct Contract;
```

• **#[contract]** is an attribute applied to the Contract struct, designating it as the type to which contract functions are associated. It implies that this struct will have contract functions implemented for it.
• **pub struct Contract;** defines a public struct named Contract. In Soroban contracts, contract functions are associated with this struct.

```
#[contractimpl]
impl Contract {
    pub fn hello(env: Env, to: Symbol) -> Vec<Symbol> {
        vec![&env, symbol_short!("Hello"), to]
    }
}
```

• **#[contractimpl]** is an attribute that is applied to the **impl** block for the **Contract** struct, indicating that this block contains the implementation of contract functions.
• **impl Contract { ... }**: This is the implementation block for the Contract struct, where contract functions are defined.
• **pub fn hello(env: Env, to: Symbol) -> Vec<Symbol> { ... }**: This line defines a public function named **hello**. It takes two arguments, **env** of type **Env** and "to" of type **Symbol**(in this case, a string of up to 8 characters). It also specifies the return type as **Vec<Symbol>**
• **{ vec![&env, symbol_short!("Hello"), to] }**: This block of code is where a length-2 vector/array containing "Hello" and then the value passed as "to" is constructed and returned.

That's all the breaks we have for today. Don't get crabby on me!(🥁)