Provides the Optional trait for Options, as well as compile-time managed Option alternatives, all generalized under the trait Maybe.

Maybe<T> is implemented for:

• Option<T>
  • Run-time managed
  • Also implements Optional and PureMaybe
• T and ()
  • Compile-time managed
  • Also implements PureStaticMaybe, PureMaybe and StaticMaybe
• [T; 1] and [T; 0]
  • Compile-time managed
  • Can be managed using constant expressions, but with some difficulty
  • Also implements StaticMaybe
• OptCell<T, _> (only if feature opt_cell is enabled)
  • Compile-time managed
  • Can be more easily managed using boolean constant expressions
  • Has const methods
  • Also implements StaticMaybe

This is how i like to handle optional function arguments with maximum flexibility.

use option_trait::*;

fn f<O>(required: i32, optional: O)
where
    O: Maybe<i32>
{
    if O::IS_MAYBE_SOME
    {
        let param = optional.unwrap_or(0);

        // This part of the code will be disabled at compile-time if the maybe cannot
        // possibly contain a value.
    }

    // Do whatever
}

f(1, 2);
f(1, ());
f(1, Some(2));
f(1, None);
f(1, [2]);
f(1, [] as [i32; 0]);
f(1, OptCell::some(2));
f(1, OptCell::none());