# Pluto
<p align="center">
<img src="./public/logos/Pluto_DARK TEXT BACKGROUND.png" alt="Pluto Logo" width="120" style="background: #fff; border-radius: 16px; box-shadow: 0 2px 8px #0002; background-color: #fff;"/>
</p>
<h1 align="center" style="color:#222; font-size:2.8em; font-weight:800; letter-spacing:-2px; margin-bottom:0.2em;">
Pluto <span style="font-size:0.6em; font-weight:400; color:#888;">Programming Language</span>
</h1>
<p align="center" style="color:#444; font-size:1.2em;">
<b>Pluto</b> is a modern interpreted programming language implemented in Rust.<br>
Designed for learning, experimentation, and rapid prototyping.<br>
<i>Simple syntax. Dynamic typing. Extensible. Fun.</i>
</p>
---
## Installation
To install Pluto, you need to have Rust installed on your system. You can install Rust using [rustup](https://rustup.rs/).
Once Rust is installed, you can clone the repository and build Pluto:
```sh
git clone https://github.com/mi66mc/pluto
cd pluto
cargo install --path .
```
or use [cargo](https://doc.rust-lang.org/cargo/getting-started/installation.html) to install Pluto directly:
```sh
cargo install pluto-lang
```
it is executed by the command `pluto-lang` in your terminal.
### Run
To run Pluto, you can use the following command:
```sh
pluto-lang
```
or
```sh
pluto-lang <filename>
```
Where `<filename>` is the path to a Pluto source file you want to execute.
---
## Features
| <b>Variables</b> | `let` keyword for variable declaration |
| <b>Block Scoping</b> | Variables are scoped to their block |
| <b>Arithmetic Expressions</b> | Supports `+`, `-`, `*`, `/`, `%`, `++`, `--`, `+=`, `-=`, `*=`, `/=` |
| <b>Floating Point Support</b> | Both integers and floats supported |
| <b>String Support</b> | String literals and concatenation |
| <b>Boolean Support</b> | `true` and `false` literals, type detection |
| <b>Function Calls</b> | Built-in and user-defined functions |
| <b>Anonymous Functions</b> | Lambda/arrow functions with `->` syntax |
| <b>Method Calls</b> | Call methods on strings, numbers, arrays, etc. |
| <b>Member Access</b> | Access module members (e.g. `Math.pi`) |
| <b>If Statements</b> | Conditional execution with `if` and `else` |
| <b>While Loops</b> | `while` loops with condition in parentheses |
| <b>For Loops</b> | C-style `for` loops with init, condition, increment |
| <b>Arrays</b> | Array literals, indexing, assignment, methods |
| <b>Comments</b> | Block comments using `/* ... */` |
| <b>Extensible</b> | Add your own built-in functions in Rust |
| <b>Simple Syntax</b> | Easy to read and write |
| <b>REPL Mode</b> | Interactive Read-Eval-Print Loop |
---
## REPL Mode
Pluto supports an interactive REPL (Read-Eval-Print Loop) mode. Simply run Pluto without any arguments:
```sh
cargo run
```
or
```sh
pluto-lang
```
You will see a prompt (`>`) where you can type Pluto code and see results immediately.
## Anonymous Functions
Pluto supports anonymous (lambda/arrow) functions using the `->` syntax. You can assign them to variables and pass them as arguments.
### Syntax
```pluto
let f = (x) -> x * 2;
print(f(10)); // 20
let square = (x) -> { x * x; };
print(square(5)); // 25
```
Anonymous functions can be used with array methods like `map`:
```pluto
let arr = [1, 2, 3];
let result = arr.map((x) -> x + 1);
print(result); // [2, 3, 4]
```
---
## Example
Given the following Pluto code in `test.po`:
```pluto
let x = 5.5;
print(x + 5);
print(x);
let a = "Result: ";
print(a);
let a = a + x;
print(a);
let abc = true;
let def = false;
print(abc, def, type(abc));
if !(5 < 2) {
print("a");
} else {
print("b");
}
print("abcde".char_at(1));
let first = input("first num: ");
let second = input("second num: ");
let sum = first.to_int() + second.to_float();
print(sum);
print(type(sum));
if sum > 10 {
print("Grather than 10!");
} else {
print("Less than 10!");
}
// User-defined function example
fn sum(a, b) {
return a + b;
}
print(sum(3, 4));
x++;
print(x);
x += 2;
print(x);
x--;
print(x);
x *= 2;
print(x);
```
**Sample Output:**
```
10.5
5.5
Result:
Result: 5.5
true false Bool
a
b
b
c
[first num prompt...]
[second num prompt...]
[sum result...]
[sum type...]
Grather than 10! or Less than 10!
7
6.5
8.5
7.5
15
```
---
## Comments
Pluto supports block comments using the `/* ... */` syntax. Everything between `/*` and `*/` will be ignored by the interpreter.
```pluto
let x = 5;
/*
This is a block comment.
It can span multiple lines.
*/
let y = x + 1; /* Inline block comment */
```
---
## While Loops
Pluto supports `while` loops with the condition enclosed in parentheses, similar to C-like languages:
```pluto
let i = 0;
while (i < 5) {
print(i);
i = i + 1;
}
```
---
## For Loops
Pluto now supports C-style `for` loops, with initialization, condition, and increment expressions, just like in C, C++, or JavaScript.
### Syntax
```pluto
for (let i = 0; i < 5; i = i + 1) {
print(i);
}
```
- The initialization, condition, and increment are separated by semicolons and enclosed in parentheses.
- The loop body can be a block (`{ ... }`) or a single statement.
### Example
```pluto
for (let i = 0; i < 10; i = i + 2) {
print(format("i = {}", i));
}
```
This will print:
```
i = 0
i = 2
i = 4
i = 6
i = 8
```
---
## Functions
Pluto supports user-defined functions using the `fn` keyword. Functions can take parameters and return values using `return`.
### Function Declaration
```pluto
fn greet(name) {
print("Hello, " + name + "!");
}
greet("Pluto");
```
### Function with Return Value
```pluto
fn add(a, b) {
return a + b;
}
let result = add(10, 20);
print(result); // 30
```
---
## Value Types
Pluto supports the following value types:
| Number | 64-bit signed integer | `let x = 42;` |
| Float | 64-bit floating point number | `let y = 3.14;` |
| String | UTF-8 string | `let s = "hi";` |
| Bool | Boolean (`true` or `false`) | `let b = true;` |
| Array | Ordered collection of values | `let arr = [1,2,3];` |
| Module | Built-in module (e.g. `Math`) | `Math.pi` |
| Function| Built-in function | `print(x);` |
You can check the type of any value using the `type` built-in function:
```pluto
let x = 5.5;
print(type(x)); // Output: Float
let b = true;
print(type(b)); // Output: Bool
let s = "hello";
print(type(s)); // Output: String
```
---
## Getting Started
### Prerequisites
- Rust (edition 2021 or later)
---
## Language Syntax
| Variable Declaration | `let x = 10;` | Declare variable `x` |
| Block Scope | `{ let y = 5; print(y); }` | Variables are scoped to blocks |
| Arithmetic | `let y = x * 2 + 3;` | Expressions with `+ - * / %` |
| Increment/Decrement | `x++; x--;` | Postfix increment/decrement |
| Assignment Operators | `x += 1; x -= 2; x *= 3; x /= 4;` | Compound assignment operators |
| String Literal | `let s = "hello";` | String assignment |
| String Concatenation | `let t = s + " world";` | Concatenate strings |
| Boolean Literal | `let b = true;` | Boolean assignment |
| Function Call | `print(y);` | Call built-in or user function |
| Function Declaration | `fn add(a, b) { return a + b; }` | Define a function |
| Return Statement | `return x + 1;` | Return from a function |
| Float Support | `let z = 3.14;` | Floating point numbers |
| If Statement | `if x > 0 { print(x); }` | Conditional execution |
| Member Access | `Math.pi` | Access module member |
| Method Call | `"abc".len()` | Call method on value |
| Input | `let s = input("prompt: ");` | Read user input |
| Array Literal | `let arr = [1, 2, 3];` | Array assignment |
| Array Indexing | `arr[0]` | Access array element |
| Array Assignment | `arr[0] = 42;` | Modify array element |
| For Loop | `for (let i = 0; i < 5; i = i + 1) { print(i); }` | C-style for loop |
---
## Built-in Functions
| print | Prints arguments to stdout | `print(x);` |
| type | Returns the type of the argument | `print(type(x));` |
| input | Reads a line from stdin | `let s = input();` |
| format | Format string with arguments | `format("Hello, {}", name)` |
| exit | Exit the interpreter | `exit(0);` |
---
## Built-in Modules
### Math
| Math.pi | Returns the value of π | `print(Math.pi);` |
| Math.pow(a, b) | Raises `a` to the power of `b` | `print(Math.pow(2, 3));` |
---
## Built-in Methods by Type
### String Methods
| len() | Returns string length | `"abc".len()` |
| to_upper() | Uppercase string | `"abc".to_upper()"` |
| to_lower() | Lowercase string | `"ABC".to_lower()"` |
| char_at(i) | Char at index `i` (as string) | `"abc".char_at(1)` |
| to_int() | Convert string to integer | `"42".to_int()"` |
| to_float() | Convert string to float | `"3.14".to_float()"` |
### Number Methods
| to_string() | Convert number to string | `x.to_string()` |
### Float Methods
| to_string() | Convert float to string | `x.to_string()` |
### Array Methods
| len() | Returns array length | `arr.len()` |
| push(val) | Returns new array with `val` added | `arr.push(5)` |
| pop() | Returns new array with last removed| `arr.pop()` |
| remove(i) | Returns new array with element at index removed| `arr.remove(2)` |
| sum() | Returns sum of numeric elements | `arr.sum()` |
| map(f) | Returns new array with function applied to each element | `arr.map((x) -> x + 1)` |
### Module Methods
Modules can contain members (constants, functions) accessible via dot notation, e.g. `Math.pi`, `Math.pow(a, b)`.
---
## Notes on Scoping
Pluto uses **block scoping** for variables. This means that variables declared with `let` inside a block (`{ ... }`) are only accessible within that block and its inner blocks. Variables declared in an outer scope are accessible in inner scopes, but not vice versa.
Example:
```pluto
let x = 1;
if true {
let y = 2;
print(x); // 1
print(y); // 2
}
print(x); // 1
print(y); // Error: y is not defined
```
---
## Contributing
Pull requests and suggestions are welcome! Please open an issue or submit a PR if you have ideas for new features, bug fixes, or improvements.
---
## License
This project is licensed under the MIT License. See [LICENSE](LICENSE) for details.
---