From ceronman@gmail.com

The following error seems to be a bug​:

$ perl6 -e 'sub one { 1 }; say one;'
===SORRY!=== Error while compiling -e
Function "one" may not be called without arguments (please use () or
whitespace to denote arguments)
at -e​:1
------> sub one { 1 }; say one⏏;

My setup​:

$ perl6 --version
This is perl6 version 2015.06 built on MoarVM version 2015.06
OS X 10.10.5

The discussion on #perl6 about it​:

[21​:55] <ceronman> Hi everyone, I just installed Perl 6 on OS X (via brew
install rakudo-star). I'm just trying the language.
[21​:55] <ceronman> while playing with it, I ran into an error when running
this​: perl6 -e 'sub one { 1 }; one;'
[21​:56] <ceronman> why is the error happening? it seems the name 'one' is
colliding with something as it doesn't happen with other function names
[21​:56] <BenGoldberg> m​: say one;
[21​:56] <+camelia> rakudo-moar 9f64ce​: OUTPUT«===SORRY!=== Error while
compiling /tmp/U9LOJjZO5d␤Function "one" may not be called without
arguments (please use () or whitespace to denote arguments, or &one to
refer to the function as a noun)␤at /tmp/U9LOJjZO5d​:1␤------> say one⏏;␤»
[21​:56] <BenGoldberg> m​: sub one { 42 }; one;
[21​:56] <+camelia> rakudo-moar 9f64ce​: OUTPUT«===SORRY!=== Error while
compiling /tmp/pTc51hLMH3␤Function "one" may not be called without
arguments (please use () or whitespace to denote arguments, or &one to
refer to the function as a noun)␤at /tmp/pTc51hLMH3​:1␤------> sub one { 42
}; o…»
[21​:56] <BenGoldberg> m​: sub one { 42 }; one();
[21​:56] <+camelia> rakudo-moar 9f64ce​: ( no output )
[21​:57] <BenGoldberg> m​: sub one { 42 }; say one.WHAT;
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«===SORRY!=== Error while
compiling /tmp/MHO9dMTX6S␤Function "one" may not be called without
arguments (please use () or whitespace to denote arguments, or &one to
refer to the function as a noun)␤at /tmp/MHO9dMTX6S​:1␤------> sub one { 42
}; s…»
[21​:57] <BenGoldberg> m​: sub one { 42 }; say &one.WHAT;
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«(Sub)␤»
[21​:57] <BenGoldberg> m​: sub one { 42 }; say &one.perl;
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«sub one () { #`(Sub|81598528)
... }␤»
[21​:57] <BenGoldberg> m​: say &one.perl;
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«sub one (+ is raw) {
#`(Sub+{<anon|49450304>}|67143056) ... }␤»
[21​:57] <BenGoldberg> m​: my $foo; one($foo);
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«WARNINGS for
/tmp/7WEXfjzD9B​:␤Useless use of "one($foo)" in expression "one($foo)" in
sink context (line 1)␤»
[21​:57] <BenGoldberg> m​: my $foo; say one($foo);
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one((Any))␤»
[21​:57] <BenGoldberg> m​: my $foo; say one($foo); say $foo
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one((Any))␤(Any)␤»
[21​:57] <BenGoldberg> m​: my $foo = ; say one($foo); say $foo
[21​:57] <+camelia> rakudo-moar 9f64ce​: OUTPUT«===SORRY!=== Error while
compiling /tmp/A0DGNFryKu␤Malformed initializer␤at
/tmp/A0DGNFryKu​:1␤------> my $foo =⏏ ; say one($foo); say $foo␤
expecting any of​:␤ prefix␤ term␤»
[21​:58] <BenGoldberg> m​: my $foo = 1; say one($foo); say $foo; # stupid
fingers
[21​:58] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one(1)␤1␤»
[21​:58] <BenGoldberg> m​: my $foo = 2; say one($foo); say $foo;
[21​:58] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one(2)␤2␤»
[21​:58] <BenGoldberg> m​: my $foo = 2; say one($foo++); say $foo;
[21​:58] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one(2)␤3␤»
[21​:58] <BenGoldberg> m​: my $foo = 2; say one(1); say $foo;
[21​:58] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one(1)␤2␤»
[21​:58] <BenGoldberg> m​: say one('what does this button do');
[21​:59] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one(what does this button
do)␤»
[21​:59] <lizmat> m​: dd one(True,False,False), one(True,True,False) #
ceronman
[21​:59] <+camelia> rakudo-moar 9f64ce​: OUTPUT«Method 'name' not found for
invocant of class 'Bool'␤ in any at gen/moar/m-Metamodel.nqp line 3124␤
in block <unit> at /tmp/hIMatcxyJm line 1␤␤»
[21​:59] <lizmat> hmmm...
[21​:59] <lizmat> m​: say one(True,False,False), one(True,True,False)
[21​:59] <+camelia> rakudo-moar 9f64ce​: OUTPUT«one(True, False,
False)one(True, True, False)␤»
[22​:00] <lizmat> m​: say so one(True,False,False), so one(True,True,False)
[22​:00] <+camelia> rakudo-moar 9f64ce​: OUTPUT«TrueFalse␤»
[22​:00] <BenGoldberg> m​: say one(1).WHAT;
[22​:00] <+camelia> rakudo-moar 9f64ce​: OUTPUT«(Junction)␤»
[22​:00] <lizmat> one() creates a junction that yields True if only one of
the values is True
[22​:01] <ceronman> I understand that, but then why if I define my own 'one'
function, I get that error?
[22​:01] <BenGoldberg> Add parens.
[22​:02] <ceronman> ok, if I type the parens, I don't get the error, but why
do I get it without the parens?
[22​:05] <lizmat> OTOH, one is just a sub in the setting... hmmm...
[22​:06] <ceronman> lizmat​: it looks like a bug. It doesn't happen with
other names, even if they collide with thigs​: perl6 -e 'sub elems { 1 };
say elems;'
[22​:12] <lizmat> ceronman​: indeed, could you please report this
rakudobug@​perl.org and quote the conversation here ?
[22​:13] <ceronman> lizmat​: I will thanks for the help

From @smls

It doesn't only happen with &one, but with all the Junction-constructing subroutines.
For example with &all​:

  ➜ sub all { 1 }; say all;
  ===SORRY!=== Error while compiling -e
  Function "all" may not be called without arguments (please use ()
  or whitespace to denote arguments, or &all to refer to the function
  as a noun)

It may have to do with their signature (as reported by the `.signature` introspection method)​:

  sub all (+ is raw)
  sub any (+ is raw)
  sub one (+ is raw)
  sub none (+ is raw)

However, the subroutine &list has the same signature, and does not suffer from this issue​:

  sub list (+ is raw)

From @zoffixznet

On Tue, 10 May 2016 14​:27​:20 -0700, smls75@​gmail.com wrote​:

It may have to do with their signature (as reported by the
`.signature` introspection method)​:

They're actually special-cased in the grammar[^1] based on their name​:

https://github.com/rakudo/rakudo/blob/4570238de7260b7360333aa216bb2b56949018fa/src/Perl6/Grammar.nqp#L3266-L3272

If it's possible to determine whether the name belongs to a non-core routine at the point where the error is emitted in the grammar, that'd be one way of avoiding the issue.

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