Your first program

Install and open a folder

Follow Get started to install the current Chelis release. Check that your terminal can find it:

chelis --version

Create a new, empty folder for the lessons. Keep it outside any existing Chelis project, including a hello-chelis checkout. A project's reef.toml can select a compiler version and make commands check the surrounding package.

mkdir chelis-lessons
cd chelis-lessons

Add two vectors

Create addition.ch in your editor and paste this source:

addition.ch

def add_vec[n](x: &tensor[n, f32], y: &tensor[n, f32]) -> tensor[n, f32] = add(x, y)
x = to_tensor([1.0f32, 2.0f32, 3.0f32])
y = to_tensor([4.0f32, 5.0f32, 6.0f32])
answer = add_vec(x, y)

chelis eval --file addition.ch

x = tensor(shape=[3], data=[1.0, 2.0, 3.0])
y = tensor(shape=[3], data=[4.0, 5.0, 6.0])
answer = tensor(shape=[3], data=[5.0, 7.0, 9.0])

The first line defines add_vec. The next two lines bind x and y to three-element tensors. The final line calls the function and binds its result to answer. These top-level bindings are what make this file a calculation you can run.

Run the commands from your lesson folder:

chelis fmt --inplace addition.ch
chelis check addition.ch
chelis eval --file addition.ch

fmt formats the source. check checks the program without evaluating it; the report's errors list should be empty. eval runs it and displays its top-level values. Find answer in the result above. Its elements come from adding the two inputs position by position.

Change the first element of y from 4.0f32 to 10.0f32. Run check and eval again. Only the first element of answer should change, from five to eleven. If nothing changes, check that you saved the file and are running it from the folder you created.

Optional: build an executable

To run this program as native code, install the compiler tools described in Install, then run:

chelis build addition.ch --output target/addition
./target/addition/addition

build invokes the native compiler and puts the executable in the output directory. It checks formatting and lint rules first. Run fmt --inplace again after an edit if the build reports a formatting error. You do not need to build an executable to follow the lessons.

Continue with shapes, reuse, precision, and derivatives.