# Functions.

# Declare.

Declare functions using `fn` keyword.

```rust
// Simple function.
fn main() {}

// With argument of type i32.
fn main(x: i32) {}

// With return type of i32.
fn main() -> i32 {}
```

# Return value.

## Return keyword.

You can return value by writing `return` keyword. Use this in multiline functions.

```rust
fn foo() -> i32
{
  return 10;
}
```

## Last expression.

It is also possible to return the result of the last line by removing `;` at the end. Use this for single-line functions.

```rust
fn foo() -> i32 { 10 }
```