Hello, World

Installing Cella

Cella installs a small launcher named cella, which manages compiler versions and runs the right one for each project. On Windows, run this in PowerShell:

irm https://anixias.github.io/Cella/install.ps1 | iex

On Linux:

curl -fsSL https://anixias.github.io/Cella/install.sh | sh

The installer puts everything in C:\cella or ~/.cella, or in CELLA_HOME if it's set, and adds cella to your path.

Windows programs link with Visual Studio's C++ build tools and the Windows SDK when they're installed, and with MinGW-w64 otherwise. Linux programs need glibc 2.34 or later.

A first program

cella new creates a project:

cella new hello

This makes a hello folder with two files. hello.celp describes the project, and main.ce holds the program:

main.ce

mod hello ext{	puts: fun(text: cstr) -> i32} main: fun -> i32{	puts("Hello, World!")	ret 0}

Output

Hello, World!

cella run builds the program and runs it:

cd hellocella run

What the program says

mod hello names the module this file belongs to. Every source file starts with a mod line, and any number of files can belong to one module.

The ext block declares puts, a function from the C library. Cella has no built-in way to print; programs call C functions, or a library that wraps them. cstr is a pointer to a zero-terminated string, which is what C expects, and a string literal converts to one.

main: fun -> i32 declares the function the program starts in. Every declaration has this shape: a name, a colon, then what the name is. fun makes it a function, and -> i32 says it returns a 32-bit integer, which becomes the program's exit code.

The body is a block of statements, one per line. Calls look as they do in C, and ret returns a value. No semicolons are needed: a new line ends a statement.

main doesn't have to return anything. Without a return type, the program exits with code 0:

mod hello ext{	puts: fun(text: cstr) -> i32} main: fun{	puts("Hello again!")}

Output

Hello again!

Printing values

printf comes from C too. Its declaration ends in ..., so it takes any number of extra arguments after the format string, and they follow C's rules for variadic calls (Variadic functions covers them). val declares a named value, covered in Variables and constants:

mod hello ext{	printf: fun(format: cstr, ...) -> i32} main: fun{	val year = 2026	val pi = 3.14159	printf("%d %.2f\n", year, pi)}

Output

2026 3.14

The rest of the documentation prints with printf. Examples leave out its ext block to stay short, but the copy button copies it along with the rest of the program.