raise

Returns early from the current function with Result::Err(e).

Using raise puts the function in result mode: its successful returns are wrapped in Result::Ok. Each function has one error type, so every raise and ? in it must agree on E. It works as a statement or an expression.

fn parse_age(int n) -> Result<int, string> {
    if n < 0 {
        raise "age cannot be negative";
    }
    return n;
}

See also#

• Result
• fn: Declares a function, a method, or (written in an expression) an anonymous function.
• let: Declares a mutable local variable.
• const: Declares a binding that cannot be reassigned: a local, a module constant, or a class field that is set only by new.
• static: Declares a module-level or class-level slot shared by the whole program, or a method without self.
• readonly: A read-only view of a value: nothing reachable through it can be changed.
• if: Runs a block when a bool condition is true.
• else: Introduces the branch of an if that runs when its condition is false (or its pattern does not match).