built-in subrule need update

[songzan]

<dot> <lt> <gt> <null> <sp> is not built-in subrule

#!perl6

use Test;

my regex dot { '.' }
my regex lt { '<' }
my regex gt { '>' }
my regex null { <?> }

ok( '.' ~~ / <dot> /, '. match <dot>');
ok( '<' ~~ / <lt> /,  '< match <lt>');
ok( '>' ~~ / <gt> /, '> match <gt>');
ok( '' ~~ / <null> /, 'blank str match <null>');

[7stud]

According to the text:

Perl 6 predeclares several useful named regex:

<alpha>     a single alphabetic character
<digit>     a single numeric character
<ident>     an "identifier"
<sp>        a single space character
<ws>        an arbitrary amount of whitespace
<dot>       a period (same as '.')
<lt>        a less-than character (same as '<')
<gt>        a greater-than character (same as '>')
<null>      matches nothing (useful in alternations that may be empty)

Your tests don't prove that they aren't predeclared. For instance, examine the following code:

~/p6_programs$ perl6 -v
This is Rakudo version 2016.11 built on MoarVM version 2016.11
implementing Perl 6.c.

~/p6_programs$ cat 4.pl6
$_ = "One   small  step";
m/One<ws>small<ws>step/;             
say $/;

my regex ws { "-" };
$_ = "One-small-step";
m/One<ws>small<ws>step/;             
say $/;

~/p6_programs$ perl6 4.pl6 
｢One   small  step｣
 ws => ｢   ｣
 ws => ｢  ｣
｢One-small-step｣
 ws => ｢-｣
 ws => ｢-｣

I redefined <ws>, but as the output shows <ws> was actually predeclared.

I think your tests would have to do something like the following:

use Test;

plan(4);

throws-like { "." ~~ /<dot>/ }, X::Method::NotFound, "Some method wasn't found in <dot> test";
throws-like { "<" ~~ /<lt>/  }, X::Method::NotFound, "Some method wasn't found in <lt> test";
throws-like { ">" ~~ /<gt>/  }, X::Method::NotFound, "Some method wasn't found in <gt> test";
throws-like { ""  ~~ /<null>/}, X::Method::NotFound, "Some method wasn't found in <null> test";

~/p6_programs$ perl6 4.pl6 
1..4
    1..2
    ok 1 - code dies
    ok 2 - right exception type (X::Method::NotFound)
ok 1 - Some method wasn't found in <dot> test
    1..2
    ok 1 - code dies
    ok 2 - right exception type (X::Method::NotFound)
ok 2 - Some method wasn't found in <lt> test
    1..2
    ok 1 - code dies
    ok 2 - right exception type (X::Method::NotFound)
ok 3 - Some method wasn't found in <gt> test
    1..2
    ok 1 - code dies
    ok 2 - right exception type (X::Method::NotFound)
ok 4 - Some method wasn't found in <null> test

Even those tests don't prove that <dot>, etc. aren't available--because the exception could be coming from another method that is failing. I'm not sure how to test for the existence of a method.