Forcing gaps between words in a Marpa grammar

Forcing gaps between words in a Marpa grammar

I'm trying to set up a grammar that requires that [\w] characters cannot
appear directly adjacent to each other if they are not in the same lexeme.
That is, words must be separated from each other by a space or
punctuation.
Consider the following grammar:
use Marpa::R2; use Data::Dump;
my $grammar = Marpa::R2::Scanless::G->new({source => \<<'END_OF_GRAMMAR'});
:start ::= Rule
Rule ::= '9' 'september'
:discard ~ whitespace
whitespace ~ [\s]+
END_OF_GRAMMAR
my $recce = Marpa::R2::Scanless::R->new({grammar => $grammar});
dd $recce->read(\'9september');
This parses successfully. Now I want to change the grammar to force a
separation between 9 and september. I thought of doing this by introducing
an unused lexeme that matches [\w]+:
use Marpa::R2; use Data::Dump;
my $grammar = Marpa::R2::Scanless::G->new({source => \<<'END_OF_GRAMMAR'});
:start ::= Rule
Rule ::= '9' 'september'
:discard ~ whitespace
whitespace ~ [\s]+
word ~ [\w]+ ### <== Add unused lexeme to match joined keywords
END_OF_GRAMMAR
my $recce = Marpa::R2::Scanless::R->new({grammar => $grammar});
dd $recce->read(\'9september');
Unfortunately, this grammar fails with:
A lexeme is not accessible from the start symbol: word
Marpa::R2 exception at marpa.pl line 3.
Although this can be resolved by using a lexeme default statement:
use Marpa::R2; use Data::Dump;
my $grammar = Marpa::R2::Scanless::G->new({source => \<<'END_OF_GRAMMAR'});
lexeme default = action => [value] ### <== Fix exception by adding lexeme
default statement
:start ::= Rule
Rule ::= '9' 'september'
:discard ~ whitespace
whitespace ~ [\s]+
word ~ [\w]+
END_OF_GRAMMAR
my $recce = Marpa::R2::Scanless::R->new({grammar => $grammar});
dd $recce->read(\'9september');
This results in the following output:
Inaccessible symbol: word
Error in SLIF parse: No lexemes accepted at line 1, column 1
* String before error:
* The error was at line 1, column 1, and at character 0x0039 '9', ...
* here: 9september
Marpa::R2 exception at marpa.pl line 16.
That is, the parse has failed due to the fact that there is no gap between
9 and september which is exactly what I want to happen. The only fly in
the ointment is that there is an annoying Inaccessible symbol: word
message on STDERR because the word lexeme is not used in the actual
grammar.
I see that in Marpa::R2::Grammar I could have declared word as
inaccessible_ok in the constructor options but I can't do that in
Marpa::R2::Scanless.
I also could have done something like the following:
Rule ::= nine september
nine ~ word
september ~ word
then used a pause to use custom code to examine the actual lexeme value
and return the appropriate lexeme depending on the value.
What is the best way to construct a grammar that uses keywords or numbers
and words but will disallow adjacent lexemes to be run together without
white space or punctuation separating them?