# Quickstart
### Installation
#### Releases
The latest releases of the Xylo binaries are available [here](https://github.com/giraffekey/xylo/releases/latest).
To ensure it is installed, check the version of the CLI in your command line.
On Linux:
```bash
cd [path]/[to]/[downloads]
./xylo_ubuntu --version
```
On macOS:
```bash
cd [path]/[to]/[downloads]
./xylo_macos --version
```
On Windows:
```powershell
cd C:\[path]\[to]\[downloads]
xylo_windows.exe --version
```
It should output the following:
```
xylo-lang 0.1.2
```
#### Cargo Install
You can install Xylo using Cargo:
```sh
cargo install xylo-lang
```
To ensure it is installed, check the version of the CLI in your command line:
```bash
xylo-lang --version
```
It should output the following:
```
xylo-lang 0.1.2
```
#### Build From Source
To build from source, ensure you have [Git](https://git-scm.com/downloads) and the [Rust programming language](https://www.rust-lang.org/tools/install) installed.
When you have the required tool set, clone and build the repository:
```bash
git clone https://github.com/giraffekey/xylo
cd xylo
cargo build --release
```
This will build the Xylo CLI in the `target` directory.
If you're on Linux, you can copy the executable into your root `/usr/bin` folder for easy access:
```bash
sudo cp target/release/xylo-lang /usr/bin/xylo
```
To ensure it is installed, check the version of the CLI in your command line:
```bash
xylo --version
```
It should output the following:
```
xylo-lang 0.1.2
```
### Writing Code
Xylo is a functional programming language. This means that it emphasizes the use of functions as the primary building blocks for constructing programs. It also means that all variables are immutable; once they are assigned, they cannot be changed.
The main function in a Xylo program is the `root` function. The purpose of the `root` function is to return a single shape or a list of shapes to be rendered to an image.
Let's get started with a simple piece of Xylo code:
```ocaml
root = FILL
```
This program renders a single `FILL` shape, which simply fills the entire image with the color white.
Save this code to a file named `art.xylo`. Then, use the following command to generate an image:
```bash
xylo generate art.xylo --width 600 --height 400
```
If all goes well, you should see a 600x400 image generated at `art.png`.
Looks good! But seems a bit empty.
Let's add a red circle to the center of the image. To do so, we can add a `CIRCLE` with a 50% lightness value. Shapes default to 100% lightness, which is always white, so if we want the circle to be visible we'll need to change its lightness with the `l` function.
```ocaml
root = FILL : l 0.5 CIRCLE
```
Here you can see that we used the `:` operator. This is called the compose operator and it can be used to compose two shapes together. In this case, we are combining the `FILL` shape with the `CIRCLE` shape.
Additionally, we are using the `l` function, which takes in two arguments. The first argument is a lightness value from 0 to 1. In this case we set it to 0.5, which means 50%. The second argument is the shape we are modifying the lightness of.
After running the generate command, you should see that `art.png` has changed.
If you look very, very closely, you should be able to see the circle. However, it's pretty small, isn't it?
Luckily, we can use the `s` function to scale the shape. All we need is an x and y value.
```ocaml
root = FILL : s 100 100 (l 0.5 CIRCLE)
```
The `s` function takes three arguments. The first and second arguments are scaling the circle by 100 pixels on the x and y axes respectively. The third argument takes in a shape; since the `l` function returns a shape, we can simply use its output.
There is a shorter way to write this code, however. Xylo also provides the `sx` function to scale only the x axis and the `sy` function to scale only the y axis. In our case, we want to scale both axes by the same value. We can use the `ss` function for this.
```ocaml
root = FILL : ss 100 (l 0.5 CIRCLE)
```
Let's run the generate command one last time. The image at `art.png` should now be similar to the Japanese flag.
Great! You're now on your way to becoming a creative coder with Xylo!
