Photo by Marc Mueller on Unsplash

Selang: an Smart Contract Programming Language for Ethereum: Introduction

After writing gelex (generic lexer), geast (generic Abstract Syntax Tree) and gepars (generic parser), using JavaScript as implementation language, I started to use these projects to design and build a simple programming language compiler: selang. As usual, I’m using TDD (Test-Driven Development) as code workflow. It helps me to follow KISS (keep-it-simple-stuped), baby steps, and emergent design.

The target of compilation is the Ethereum Virtual Machine. The process of compilation is:

Current implementation is still incomplete, but a sample with code, compilation, deploy and invocation is here.

The code of the simple contract is

contract Counter {
    uint counter;
        
    public uint getCounter() {
        return counter;
    }
    
    public void increment() {
        counter = counter + 1;
    }
        
    public void add(uint value) {
        counter = counter + value;
    }
}

You can compile the code with

node compile

And you can compile, deploy to http://localhost:8545 (usually a ganache-cli node instance), and invoke it, executing:

node deploy

The only type supported is uint (unsigned 32 bytes integer). Next steps:

• Support for other numeric types
• Support for static and dynamic arrays (a bit challenging, memory management with bytecodes)
• Support for strings (another challenge: using keccak256 hash functions to allocate dynamically the string in 32-bytes storage cells)
• Constructor code (it’s code that is used only once, and should be compiled in different ways)
• Inheritance

Related posts:

• Gelex, a generic lexer in JavaScript
• Geast, a generic Abstract Syntax Tree
• Gepars, a generic parser

Angel “Java” Lopez
https://github.com/ajlopez
https://twitter.com/ajlopez