English.pm

grammar Parser::English
{
	rule TOP { <sentence> };
	
	rule sentence
	{
		  <noun_phrase> <verb_phrase>
		| <noun_phrase> <auxillary> <verb_phrase>
		| <auxillary> <noun_phrase> <verb_phrase> 
	};
	
	rule noun_phrase { <determiner>? <adjective_phrase>? <noun> <prepositional_phrase>? };
	rule verb_phrase { <verb> <noun_phrase>? <prepositional_phrase>? };
	rule prepositional_phrase { <preposition> <noun_phrase> };
	rule adjective_phrase { <adverb_phrase>? <adjective> };
	rule adverb_phrase { <adverb> <adverb_phrase>? };

	rule auxillary { <verb> };

	rule noun { noun <rest> };
	rule verb { verb <rest> };
	rule adjective { adjective <rest> };
	rule adverb { adverb <rest> };
	rule preposition { preposition <rest> };
	rule determiner { determiner <rest> };
	rule rest { \|?.*?\s? };
};

test.pl

use v6;
use Test;

use Parser::English;

ok Parser::English.parse('noun verb'),                                 'Passes';
nok Parser::English.parse('noun adverb'),                              'Passes';

ok Parser::English.parse('noun|verb verb'),                            'Passes';
ok Parser::English.parse('noun|verb noun|verb preposition noun|verb'), 'Passes';
ok Parser::English.parse('determiner adjective|adverb noun verb'),     'Fails';

done_testing;