Version: 1.1.0

Variables

A Mojo variable is introduced with var. The name is fixed to one type for its whole lifetime.

Essentials

• Write var score = 0 and Mojo infers Int.
• Write var score: Int when you need the name before it has a value, then initialize it on every path.
• Assignment updates the value. It does not change the type.
• Names that start with an underscore are treated as private by convention.

Example

def main():
    var total: Int = 0
    for i in range(10):
        total += i
    print(total)

Keep in mind

If a name is used before it is initialized on every path, compilation fails. That check is what keeps late bugs out of runtime.