perl - perl6/rakudo: Problem with writing on the loop-variable -

#!perl6 use v6;  $longest = 3; @list = <a b c d e f>;  @list -> $element rw {     $element = sprintf "%*.*s", $longest, $longest, $element;     $element.say; } 

this works. in second , third error-message. how make them work?

#!perl6 use v6;  $longest = 3; @list = <a b c d e f>;  @list <-> $element {     $element = sprintf "%*.*s", $longest, $longest, $element;     $element.say; }  # ===sorry!=== # missing block @ line 11, near "" 

.

#!perl6 use v6;  $longest = 3; $list = <a b c d e f>;  $list.list -> $element rw {     $element = sprintf "%*.*s", $longest, $longest, $element;     $element.say; }  # cannot modify readonly value #   in '&infix:<=>' @ line 1 #   in <anon> @ line 8:./perl5.pl #   in main program body @ line 1 

regarding second example

the <-> may not have worked in rakudo perl used, has been fixed in more recent versions. (it had deep parsing issue required better longest-token-matching algorithm had @ time.)

regarding third example

the statement

my $list = <a b c d e f>; 

creates $list seq data type, , seq elements considered immutable. want $list become array, in:

my $list = [<a b c d e f>]; 

with in place, last example works expected:

pmichaud@orange:~/rakudo$ cat x.p6 #!perl6 use v6;  $longest = 3; $list = [<a b c d e f>];  $list.list -> $element rw {     $element = sprintf "%*.*s", $longest, $longest, $element;     $element.say; }  pmichaud@orange:~/rakudo$ ./perl6 x.p6     b   c   d   e   f pmichaud@orange:~/rakudo$  

hope helps!

pm