Macro set_slice 

macro_rules! set_slice {
    (@$($ln:tt),* => unsafe $slice:ident: ($size:expr) = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident = move $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident = $option:ident $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident = $($value:expr),+; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => unsafe $slice:ident[$($range:tt)*]: ($size:expr) = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*] = move $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*] = $option:ident $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*] = $($value:expr),+; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => unsafe $slice:ident[$($range:tt)*]: ($size:expr) = $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => unsafe $slice:ident: ($size:expr) = $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*]: ($size:expr) = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident: ($size:expr) = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*] = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident= ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => unsafe $slice:ident[$($range:tt)*] = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => unsafe $slice:ident= ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident: $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident = ref $value:expr; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident = ; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*]: $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*] = ; $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $slice:ident[$($range:tt)*] $($rest:tt)*) => { ... };
    (@$($ln:tt),* => ) => { ... };
    () => { ... };
    (@$($ln:tt),* => [$($range:tt)*] $($rest:tt)*) => { ... };
    (@$($ln:tt),* => $($rest:tt)+) => { ... };
    ($($rest:tt)+) => { ... };
}

a macro for setting parts of slices, see crate level docs for more info