From pim.mouss@free.fr

Hi,

playing with pugs and parrot compiled perl6 i found this bug​:

1st script :

#!/usr/local/bin/pugs -w

loop (my $i=0;$i<2;$i++) {
say $i;
}

works well.

2nd script :

#!/usr/local/bin/pugs -w

my $n=7;
if ($n > 2) { say "$n is bigger than 2";}

works well.

3rd script (is the concatenation of both 1st and 2nd)​:

#!/usr/local/bin/pugs -w

loop (my $i=0;$i<2;$i++) {
say $i;
}

my $n=7;
if ($n > 2) { say "$n is bigger than 2";}

crashes with this error​:
pugs t3.pl
***
  Unexpected "2"
  expecting operator or ";"
  at ./t3.pl line 9, column 10

Here's my pugs version : Version​: 6.2.13.11 according pugs -v.

and per6 parrot compiled (THIS VERSION)​:
This is Rakudo Perl 6, revision 30402 built on parrot 0.7.0-devel
11​:57 < pim> for i486-linux-gnu-thread-multi.
complains like this​:
Statement not terminated properly at line 9, near "2) { say \""

current instr.​: 'parrot;PGE​::Util;die' pc 119 (runtime/parrot/library/PGE/Util.pir​:82)
called from Sub 'parrot;Perl6​::Grammar;eat_terminator' pc 23817
(src/gen_grammar.pir​:2840) called from Sub 'parrot;Perl6​::Grammar;statementlist' pc 22866
(src/gen_grammar.pir​:2473) called from Sub 'parrot;Perl6​::Grammar;circumfix' pc 77039
(src/gen_grammar.pir​:23163) called from Sub 'parrot;Perl6​::Grammar;noun' pc 64913
(src/gen_grammar.pir​:18584) called from Sub 'parrot;Perl6​::Grammar;expect_term' pc 60176
(src/gen_grammar.pir​:16796) called from Sub 'parrot;PGE​::OPTable;parse' pc 1959
(compilers/pge/PGE/OPTable.pir​:554)called from Sub 'parrot;Perl6​::Grammar;arglist' pc 92058
(src/gen_grammar.pir​:29009) called from Sub 'parrot;Perl6​::Grammar;term' pc 67012
(src/gen_grammar.pir​:19356) called from Sub 'parrot;Perl6​::Grammar;noun' pc 65511
(src/gen_grammar.pir​:18786) called from Sub 'parrot;Perl6​::Grammar;expect_term' pc 60176
(src/gen_grammar.pir​:16796) called from Sub 'parrot;PGE​::OPTable;parse' pc 1959
(compilers/pge/PGE/OPTable.pir​:554) called from Sub 'parrot;Perl6​::Grammar;statement' pc 24619
(src/gen_grammar.pir​:3146) called from Sub 'parrot;Perl6​::Grammar;statementlist' pc 22764
(src/gen_grammar.pir​:2437) called from Sub 'parrot;Perl6​::Grammar;statement_block' pc 20803
(src/gen_grammar.pir​:1665)called from Sub 'parrot;Perl6​::Grammar;TOP' pc 17136 (src/gen_grammar.pir​:225)
called from Sub 'parrot;PCT​::HLLCompiler;parse' pc 585
(src/PCT/HLLCompiler.pir​:371) called from Sub 'parrot;PCT​::HLLCompiler;compile' pc 438
(src/PCT/HLLCompiler.pir​:303) called from Sub 'parrot;PCT​::HLLCompiler;eval' pc 776
(src/PCT/HLLCompiler.pir​:473) called from Sub 'parrot;PCT​::HLLCompiler;evalfiles' pc 1078
(src/PCT/HLLCompiler.pir​:610) called from Sub 'parrot;PCT​::HLLCompiler;command_line' pc 1257
(src/PCT/HLLCompiler.pir​:699) called from Sub 'parrot;Perl6​::Compiler;main' pc 15352 (perl6.pir​:172)

Hope this paste is not too long.

Notice : i talked about this error on irc #perl6 and they proposed me to post
the bug here.

Kind regards.
Jean-Yves.

From @pmichaud

On Wed, Sep 03, 2008 at 03​:38​:29AM -0700, Pim wrote​:

#!/usr/local/bin/pugs -w

loop (my $i=0;$i<2;$i++) {
say $i;
}

my $n=7;
if ($n > 2) { say "$n is bigger than 2";}
------------------
crashes with this error​:
Unexpected "2"
expecting operator or ";"
at ./t3.pl line 9, column 10
[...]
and per6 parrot compiled (THIS VERSION)​:
Statement not terminated properly at line 9, near "2) { say \""

If both pugs and rakudo agree on an error, I'd bet that the
problem is in the program and not the compiler(s). :-)

In this case, the problem is the lack of a space before the
angle bracket in the loop statement​:

  loop (my $i=0;$i<2;$i++) {
  ...
  if ($n > 2) { say "$n is bigger than 2";}

Perl 6 sees the angle bracket following the "$i" as being a
subscript using the <...> notation, which ends at the angle
bracket in the "if" statement. It then complains about not
understanding the "2" that follows the closing angle bracket.

S03​:2793 notes this explicitly​:

  Note​: any operator beginning with C<< < >> must have whitespace
  in front of it, or it will be interpreted as a hash subscript instead.

So, add a whitespace character in front of the opening angle bracket,
and all works (at least in rakudo)​:

  $ cat x
  #!/usr/local/bin/pugs -w
 
  loop (my $i = 0; $i < 2; $i++) {
  say $i;
  }
 
  my $n = 7;
  if ($n > 2) { say "$n is bigger than 2";}
 
  $ ./parrot perl6.pbc x
  0
  1
  7 is bigger than 2

Thanks!

Pm

The RT System itself - Status changed from 'new' to 'open'

From @masak

Patrick (>)​:

If both pugs and rakudo agree on an error, I'd bet that the
problem is in the program and not the compiler(s). :-)

In this case, the problem is the lack of a space before the
angle bracket in the loop statement​:

loop (my $i=0;$i<2;$i++) {
...
if ($n > 2) { say "$n is bigger than 2";}

Perl 6 sees the angle bracket following the "$i" as being a
subscript using the <...> notation, which ends at the angle
bracket in the "if" statement. It then complains about not
understanding the "2" that follows the closing angle bracket.

S03​:2793 notes this explicitly​:

Note​: any operator beginning with C<< < >> must have whitespace
in front of it, or it will be interpreted as a hash subscript instead.

So, add a whitespace character in front of the opening angle bracket,
and all works (at least in rakudo)​:

$ cat x
#!/usr/local/bin/pugs -w

loop (my $i = 0; $i < 2; $i++) {
say $i;
}

my $n = 7;
if ($n > 2) { say "$n is bigger than 2";}

$ ./parrot perl6.pbc x
0
1
7 is bigger than 2

There's a related problem when using empty parens after the 'loop'
keyword, however​:

$ cat test.p6
loop () {
}
my $n

$ ./perl6 test.p6
Statement not terminated properly at line 1, near "{\n}\nmy $n\n"
[...]

That can't be related to the <...> notation. Are empty parens allowed here?

// Carl

From @pmichaud

On Wed, Sep 03, 2008 at 03​:26​:03PM +0200, Carl Mäsak wrote​:

Patrick (>)​:

If both pugs and rakudo agree on an error, I'd bet that the
problem is in the program and not the compiler(s). :-)

In this case, the problem is the lack of a space before the
angle bracket in the loop statement​:

There's a related problem when using empty parens after the 'loop'
keyword, however​:

$ cat test.p6
loop () {
}
my $n

$ ./perl6 test.p6
Statement not terminated properly at line 1, near "{\n}\nmy $n\n"
[...]

That can't be related to the <...> notation. Are empty parens allowed here?

According to STD.pm, empty parens aren't allowed -- the semicolons
are required. One can write an infinite loop as either

  loop { ... }

or

  loop (;;) { ... }

At present Rakudo understands the first form but not the second
(patches welcome -- mainly the grammar just needs to treat the
expressions as optional instead of required).

Thanks!

Pm

From jswitzer@gmail.com

That can't be related to the <...> notation. Are empty parens
allowed here?

According to STD.pm, empty parens aren't allowed -- the semicolons
are required. One can write an infinite loop as either

loop \{ \.\.\. \}

or

loop \(;;\) \{ \.\.\. \}

At present Rakudo understands the first form but not the second
(patches welcome -- mainly the grammar just needs to treat the
expressions as optional instead of required).

As of index 78b38ad..61c292d, both forms of the infinite loop function
as described. According to the grammer, expressions e1, e2, and e3 are
all optional, making that second form valid.

I'm closing this ticket since the original source was missing the
disambiguating space before C<< < >> and the infinite loops work.

jswitzer@gmail.com - Status changed from 'open' to 'resolved'