Macro define_function

macro_rules! define_function {
    ($name:ident, args: [], $body:expr) => { ... };
    ($name:ident, args: [$arg_type:ty], $body:expr) => { ... };
    ($name:ident, args: [$arg_type1:ty, $arg_type2:ty], $body:expr) => { ... };
    ($name:ident, args: [$arg_type1:ty, $arg_type2:ty, $arg_type3:ty], $body:expr) => { ... };
    ($name:ident, args: [$arg_type1:ty, $arg_type2:ty, $arg_type3:ty, $arg_type4:ty], $body:expr) => { ... };
}

Two-macro solution for better type safety and clarity

Macro for functions that return Result<T, E> Uses .map() conversion for Result types