Left      Right      Description and pseudocode
        ===============================================================
[...]
        Any       ARRAY      smartmatch each ARRAY element[3]
                       like: grep { Any ~~ $_ } ARRAY

##</code><code>##

        Left      Right      Description and pseudocode
        ===============================================================
[...]
        Any       Num        numeric equality
                        like: Any == Num
        Num       nummy[4]    numeric equality
                        like: Num == nummy
        undef     Any        check whether undefined
                        like: !defined(Any)
        Any       Any        string equality
                        like: Any eq Any

##</code><code>##

        nummy[4]  Num        numeric equality
                        like: nummy == Num