my ( $first, @list ) = @{my_list};
treat_1( $first );
treat_others( $_ ) for @list;
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If $my_list can be destroyed, it can be made shorter.

treat_1( shift @$my_list );
treat_others( $_ ) for @$my_list;
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If it cannot be destroyed, it can still be done without the temporary variables:

treat_1( $my_list->[0] );
treat_others( $my_list->[$_] ) for ( 1 .. $#{$my_list} );
[download]

Update: Added a couple of more different implementations.