Macro frappe::sample_with

macro_rules! sample_with {
    (@impl $f:expr ; ; $($var:ident)+) => { ... };
    (@impl $f:expr ; $sig:expr, $($tail:expr,)* ; $($var:ident)*) => { ... };
    (@named ; ; $e:expr) => { ... };
    (@named $sig:expr, $($stail:expr,)* ; $var:ident $($vtail:ident)* ; $e:expr) => { ... };
    ($($sig:expr),+ ; $f:expr) => { ... };
    ($($sig:expr),+ => | $($var:ident),+ | $e:expr) => { ... };
}

Helper for using Signal::sample_with with multiple signals.

Called as: sample_with!(s1, s2, ...; f) where:

• s1: Signal<S1>, s2: Signal<S2>, ... are N input signals
• f(MaybeOwned<S1>, MaybeOwned<S2>, ...) -> R is a function that takes N arguments

or as: sample_with!(s1, s2, ... => |v1, v2, ...| expr) where:

• v1: MaybeOwned<S1>, v2: MaybeOwned<S2>, ... are N variable names
• expr is an expresion using those variables