Steel Language v2.0

Steel is a simple, readable programming language designed to be easy to learn and intuitive to use. It focuses on clean syntax, minimal complexity, and fast execution through a custom JavaScript interpreter.

Install

npm install steel-lang-2

Features

• Variables: set x to 10
• Output: say "Hello!"
• Template Strings: `Hello ${name}!`
• Conditionals: if / elseif / else / end
• Loops: while / for / for each / repeat
• Functions: define name as (params) ... return value end with closures and recursion
• Arrays: [1, 2, 3] with index access, set arr[0] to val
• Full Operators: + - * / % > < >= <= == != and or not
• Comments: // line comments
• Booleans: true, false, null
• Operator Precedence: Proper precedence climbing (multiplication before addition, etc.)

Built-in Functions

Math

abs, round, floor, ceil, sqrt, pow, min, max, random, pi, e

String

len, upper, lower, trim, substring, replace, split, join, contains, charAt, indexOf, startsWith, endsWith, repeat, padStart, padEnd

Array

push, pop, shift, unshift, reverse, sort, slice, includes, flat, range

Type

type, isNumber, isString, isArray, toString, toNumber

Misc

clock, sleep, input

Quick Start

git clone https://github.com/magnexis/Steel-lang.git
cd Steel-lang
node src/index.js examples/hello.steel

Example

// Variables and types
set name to "Steel"
set version to 2

// Functions with recursion
define factorial as (n)
  if n <= 1 then
    return 1
  end
  return n * factorial(n - 1)
end

say factorial(10)  // 3628800

// Arrays and loops
set nums to [1, 2, 3, 4, 5]
for each n in nums
  say n * n
end

// Higher-order patterns
define sum as (arr)
  set total to 0
  for each val in arr
    set total to total + val
  end
  return total
end

say sum(range(1, 101))  // 5050

Project Structure

steel-lang/
├── src/           # Language engine
│   ├── lexer.js       # Tokenizer
│   ├── parser.js      # Recursive descent parser with precedence climbing
│   ├── interpreter.js # Tree-walking interpreter
│   ├── environment.js # Scope, built-ins, function closures
│   └── index.js       # CLI entry point
├── examples/      # Example programs
│   ├── hello.steel
│   ├── logic.steel
│   ├── variables.steel
│   ├── features-demo.steel
│   ├── control-flow.steel
│   └── functions-arrays.steel
└── stl/           # VS Code extension

License

MIT