arr

arrcomp

Macro arr 

Source 
macro_rules! arr {
    ($ex:stmt, for $x:pat in $input:expr $(, if $cond:expr)+; len $len:expr) => { ... };
    ($ex:stmt, for $x:pat in $input:expr; len $len:expr) => { ... };
}
Expand description

The arr! macro has two branches - one for filtered comprehensions and one for unfiltered. This distinction allows unfiltered comprehensions to return arrays of a base type rather Option<type>, simplifying cases where all values would be Some

arr![$ex, for $x in $input, if $cond0, if $cond1; len $len]