use strict;

sub functional_FY {
  return @_ if @_ < 2;
  my $i = rand @_;
  @_[ 0, $i ] = @_[ $i, 0 ];
  return ( shift, functional_FY( @_ ) );
}

print "@{ [ functional_FY( 1..10 ) ] }\n";

##</code><code>##

sub functional_FY {
  return @_ if @_ < 2;
  return ( splice( @_, rand @_, 1 ), &functional_FY );
}

##</code><code>##

sub functional_FY {
  return @_ < 2 ? @_ : ( splice( @_, rand @_, 1 ), &functional_FY );
}