my @y = map { state $z = 0; $z += $_ } @x;

##</code><code>##

>perl -wMstrict -MData::Dump -lE
"sub summer { return map { state $z = 0;  $z += $_; } @_; }
 ;;
 my @w = qw(0 1 3 2);
 my @x = summer(@w);
 my @y;  @y = map { state $z = 0;  $z += $_; } @w for 1 .. 3;
 my @z = map { state $z = 0;  $z += $_; } @w;
 ;;
 dd \@w;
 dd \@x;
 dd \@y;
 dd \@z;
 ;;
 @x = summer(@w);
 @y = map { state $z = 0;  $z += $_; } @w for 1 .. 3;
 @z = map { state $z = 0;  $z += $_; } @w;
 ;;
 print '----------';
 dd \@w;
 dd \@x;
 dd \@y;
 dd \@z;
 ;;
 print '----------';
 dd \@w;
"
[0, 1, 3, 2]

[0, 1, 4, 6]

[12, 13, 16, 18]

[0, 1, 4, 6]

----------
[0, 1, 3, 2]

[6, 7, 10, 12]

[12, 13, 16, 18]

[0, 1, 4, 6]

----------
[0, 1, 3, 2]