sub foo {
    my $wa = wantarray;
    if    ( $wa )         { print "array\n"  }
    elsif ( defined $wa ) { print "scalar\n" }
    else                  { print "void\n"   }
}

my @x = ( 1, 2 );

print "for(\@x){foo()}:\n";
for ( @x ) { foo( $_ ) }      # void
print "map{foo()} \@x:\n";
map { foo( $_ ) } @x;         # array
__END__
for(@x){foo()}:
void
void
map{foo()} @x:
array
array