Type aliases

type Count = i32

def increment(value: Count) -> Count:
    value + Count(1)

type Name = Type declares a transparent, non-generic module-level alias to a supported type or another alias. Aliases are visible throughout the module and may refer forward. Unknown targets, cycles, duplicate aliases, and declaration or built-in name collisions are rejected even when the alias is unused. Local aliases are unsupported.

An alias adds no nominal identity, validation, or runtime wrapper. Two aliases for i32 are interchangeable with each other and i32. Existing storage and visibility restrictions apply through aliases.

Aliases work in signatures and local annotations. Numeric aliases support their target’s cast syntax and conversion semantics. Boolean, string, and unit aliases add no constructors or conversions.

Aliases do not change literal defaults or introduce suffixes: x: Count = 42 uses the annotation as context, while 42Count is invalid. A local expression name may shadow Count without changing its meaning in a type annotation.