use strict;
use Parse::RecDescent;

my $grammar = q(
     START: ( number | word )+
     word: /\w+/ { print "found a word\n"; }
     number: /\d+/ { print "found a number\n"; }
);

Parse::RecDescent->new($grammar)->START("123 geo 456 bam");
[download]

D:\>perl
use strict;
use Parse::RecDescent;

my $grammar = q(
     START: ( number | word )+
     word: /\w+/ { print "found a word\n"; }
     number: /\d+/ { print "found a number\n"; }
);

Parse::RecDescent->new($grammar)->START("123 geo 456 bam");

__END__

       ERROR (line 2): Untranslatable item encountered: "+"
                (Hint: Set $::RD_HINT (or -RD_HINT if you're using "pe
+rl -s")
                       for hints on fixing these problems.)
Can't call method "START" on an undefined value at - line 10.

D:\>perl
$::RD_HINT=1;
use strict;
use Parse::RecDescent;

my $grammar = q(
     START: ( number | word )+
     word: /\w+/ { print "found a word\n"; }
     number: /\d+/ { print "found a number\n"; }
);

Parse::RecDescent->new($grammar)->START("123 geo 456 bam");

__END__

       ERROR (line 2): Untranslatable item encountered: "+"
                (Hint: Did you misspell "+" or forget to comment it ou
+t?)
Can't call method "START" on an undefined value at - line 11.

D:\>perl
$::RD_HINT=1;
use strict;
use Parse::RecDescent;

my $grammar = q(
     START: ( number | word )(s)
     word: /\w+/ { print "found a word\n"; }
     number: /\d+/ { print "found a number\n"; }
);

Parse::RecDescent->new($grammar)->START("123 geo 456 bam");

__END__
found a number
found a word
found a number
found a word
[download]

Subrules may also be specified with a trailing repetition specifier, indicating that they are to be (greedily) matched the specified number of times. The available specifiers are:

subrule(?)      # Match one-or-zero times
subrule(s)      # Match one-or-more times
subrule(s?)     # Match zero-or-more times
subrule(N)      # Match exactly N times for integer N > 0
subrule(N..M)   # Match between N and M times
subrule(..M)    # Match between 1 and M times
subrule(N..)    # Match at least N times
[download]

Thank you very much , anonymous monk !