boson

An interpreted, dynamically-typed, multi-threaded, general purpose hobby programming language written in Rust.

Check out the live web server written in boson-lang:

To experiment with the capabilities of boson, I wrote a simple TCP single threaded web server which serves a sample HTML document. Check out this URL (The static web server is packaged as a container image and is deployed on Heroku)

• Live demo
• Source code can be found here
• Multithreaded web server

Features:

1. Multiple Data Types: char, int, float, string, array, hashtable, bytes and buffer
2. Airthmetic, Logical operations
3. Variables and Constants
4. Control and Looping structures
5. Functions and Lambda expressions
6. Many built-in functions
7. Threads and Multi-threading
8. Shell operator to run shell commands within the language statements
9. Some basic built-in functions
10. Iterators (psuedo iterators)
11. Byte code generation, serialization and loading
12. Dynamic modules - can load rust modules at runtime as addons
13. System calls

Note: The documentation of this project is still in early stages.

Installation:

Building the language from source requires a working rust toolchain installed on the host machine. Check out the tutorial here to set-up Rust and Cargo.

1. Grab the source code:

git clone git@github.com:Narasimha1997/boson-lang.git

2. Build boson:

./build.sh

The build script should install Boson suite of tools on your system. Explore different options supported by this script.

3. Run sample source code

boson-eval examples/hello.np

This should print hello, world! on screen.

Using the tools

If compilation is successful, it should generate four binary tools, these are:

1. boson: This is the REPL of boson lang, you can execute boson language statements in the CLI.

Welcome to Boson REPL
This is a REPL binary for boson - a general purpose programming language written in rust. (Ctrl + C to quit)
Boson v0.0.1
VM Check - Passed.
>> println(10 + 20)
30

2. boson-dis: This tool generates stringified representation of the compiled version of source file.

boson-dis examples/hello.np

This should generate the output:

Instructions: 
00000000 IConstant 0
00000003 ILoadBuiltIn 2
00000006 ICall 1

Constants: 
00000000 hello, world!

3. boson-compile: This tool generates the compiled bytecode of the source file, which can then be executed.

boson-eval ./examples/hello.np

This should generates a file called hello.np.b in the same folder hello.np was present, i.e examples/hello.np.b. This file has the binary representation of the compiled bytecode.

4. boson-eval: Evaluates the source file or the bytecode file and stdouts the result.

boson-eval ./examples/hello.np

Language examples:

1. Hello, world

println('hello,world')

2. Keyboard input and display

const ip = input()
const ip2 = input();
const greeting = "Hello! " + ip2 + " " + ip;
println(greeting);

3. Arithmetic operators

const d = a + b + c;
const e = a * b - c;
const f = ((a + b) * c * d) / (a + b);

const g = (a + b) % c;

println(a, b, c, d, e, f, g); # 1 2 3 6 -1 18 0

4. Bitwise operators

const x = 10;
const y = 20;

var z = ((x & 0) | y);
println(~z) # -21

5. Logical operators

const m = 10;
const n = 20;

println(m > n, n < m, n > m + 5) # false, false, true
println(m == n - 10, !0, !(m == n - 10)) # true true false

6. Arrays

var array = [1, 2, 3, 4, "Hello", 6.455]
println(array[0] + 2) # 3
println(array[4] + ", world") # Hello, world
println(array) # Array([1, 2, 3, 4, Hello, 6.455])

array[4] = 9678967;
println(array) # Array([1, 2, 3, 4, 9678967, 6.455])

7. Hash tables

var myHashMap = {
    "name": "Prasanna",
    "age": 24,
    "country": "India"
}

println(myHashMap) # HashTable({age: 24, country: India, name: Prasanna})
println(myHashMap["age"] + 2) # 26

const key = "name"
println("Hey! " + myHashMap[key]) # Hey! Prasanna

myHashMap["city"] = "Bengaluru"
println(myHashMap["city"]) # Bengaluru

8. While loop

const N = 100;

var n0 = 0;
var n1 = 1;
var n2 = 0;
var idx = 2;

while (idx <= N ) {
    n2 = n0 + n1;
    n0 = n1;
    n1 = n2;
    idx = idx + 1;
}

println(n1);

9. If else:

const x = 10;

if (x > 20) {
    println("X > 20");
} else {
    println("X < 20"); # this will be executed
}

10. Functions:

func fib(N) {
    
    if (N == 0) {
        return 0;
    }

    if (N == 1) {
        return 1;
    }

    return fib(N - 1) + fib(N - 2);
}

const result = fib(10);
println('got result: ', result);

11. Shell operator:

Shell operator can be used to execute shell commands within the program statements.

# count the number of files in the given directory
func count_files() {
    const res = $ "ls | wc -l";
    return int(res[1]);
}

# call the function and print it's output
println(count_files());

# count the number of occurences of a given pattern in the given file
func count_occurences(file, pattern) {
    const res = $ "cat "+file+" | grep -c "+pattern; 
    return int(res[1])
}

const res = count_occurences("LICENSE", "GPL")
println(res);

12. Lambda functions:

# define a adder that takes two parameters
const lambda_adder = lambda x, y => x + y
println(lambda_adder(10, 20)) # 30

13. Functions as objects:

# here the adder function accepts a function as argument and executes it
func adder_exec(fn, x, y) {
    return fn(x, y)
}

# adder function is defined here
func adder(x, y) {
    return x + y
}

# adder function is passed as the parameter
const result = adder_exec(adder, 10, 20)
println(result) # 30

14. Closures:

# this is the wrapper function that returns a adder function with enclosed local variables
func wrap_adder(x, y) {
    const z = 30
    func adder() {
        return x + y + z
    }

    return adder
}

# call the wrapper and obtain the inner child
const adder = wrap_adder(10, 20)

# call the inner child adder function
const result = adder()
println(result) # result = 60

15. Iterators:

Note: Iterators are yet to be tested completely

const arr = [1, 2, 3, 4]
const iterator = iter(arr)
while (has_next(iterator)) {
    println(next(iterator))
}

16. Multithreading:

# this function prints Hello, world from <thread> every 3 seconds 
func print_periodic(name) {
    while (true) {
        println("Hello, world from ", name);
        sleep_sec(3);
    }
}

# spawn thread1 and spawn thread2
const th1 = thread print_periodic("thread1");
const th2 = thread print_periodic("thread2");

# wait for thread 1 and thread 2 to complete
wait(th1)
wait(th2)

Threads and global variables: In boson, every thread gets it's own copy of global variables space, so when a thread mutates a global variable, it mutates it's local variable copy and not the one in global space.

Native modules

Boson has a support for native modules written in Rust, every module has to implement a set of functions as per the standard function signatures shown below:

pub type OpenFunctionSymbol = unsafe extern "Rust" fn(Rc<Object>) -> DynamicModuleResult;
pub type CloseFunctionSymbol = unsafe extern "Rust" fn(Rc<Object>) -> DynamicModuleResult;
pub type ReadFunctionSymbol = unsafe extern "Rust" fn(Rc<Object>) -> DynamicModuleResult;
pub type WriteFunctionSymbol = unsafe extern "Rust" fn(Rc<Object>) -> DynamicModuleResult;
pub type ExecFunctionSymbol = unsafe extern "Rust" fn(String, &Vec<Rc<Object>>) -> DynamicModuleResult;

Any cargo crate that implements these functions can be loaded and used as a dynamic module. Look at the hello-world module for reference. Make sure you add the following lines to Cargo.toml of the cargo crate you are trying to build as a module:

[lib]
crate-type = ["rlib", "cdylib"]

The native modules that are under modules/ directory will be installed at /usr/local/lib/boson and can be loaded using mopen:

# you can pass init parameters also while calling `mopen`
const regex = mopen("std::re", none)[0];

This will look for libre.so in /usr/local/lib/boson, in general it will look at /usr/local/bin/boson/lib{{module-name}}.so. However you can also load modules directly by their file-paths like:

const regex = mopen("/usr/local/lib/boson/libre.so", none)[0];

System calls

System call methods are provided as builtin functions in boson. get_syscalls method returns a list of all the system calls supported on the target architecture and syscall method executes the system call. Look at the example below:

const no = get_syscalls();
const fd = syscall(no.OPEN, "hello.txt", 0)

if (fd < 0) {
    println("file hello.txt not found")
    exit(fd)
}

const buffer = create_buffer(10)

syscall(
    no.READ,
    fd, 
    buffer,
    10
)

println(string(buffer))

Embedding Boson:

Boson language compiler + VM can be easily integrated into other projects using the API. As of now, any Rust codebase can import statically the Boson crate or use foreign function interface (FFI) to load Boson shared library by manually defining the ABI. We are yet to test CXXABI compatibility of the boson crate, so it can be considered unsafe to import boson in Non-Rust codebases as of now.

Here is how you can embed boson in other rust projects:

extern crate boson;

use boson::api::BosonLang;

pub fn main() {
    let result = BosonLang::eval_buffer(
        "10 + 3 / 2"
            .as_bytes()
            .to_vec()
    );

    println!("eval result: {}", result);
    // will output "eval result: Some(Float(11.5))"
}

Running tests

You can use cargo test tools to run the test

cargo test

Benchmarks

Benchmarks are still under implementation

Credits

1. Monkey lang
2. Monkey lang rust version

TODO:

1. Web assembly port
2. Proper documentation
3. Proper test cases
4. Bug fixes

Contributing

Feel free to raise any issues, make Pull Requests, suggest changes, clone the project and make your own changes.