My understanding of English grammar is that a comma should not precede an 'and' statement when describing a list - If I am mistaken on this understanding, please feel free to enlighten me. Be that the case however, I would rewrite your function as follows:

sub serial
{
    join( ', ', @_[ 0..$#_-1 ] ) . 
        ( @_ > 1 ? ' and ' : '' ) .
        $_[-1]
}
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perl -le 'print+unpack("N",pack("B32","00000000000000000000001001001011"))'

This is one of those old raging debates. I used to be in the camp you describe, but came around over time b/c the serial comma is clearer grammatically. It is more flexible too and allows things like, "exotic reptiles, cats and dogs, arachnids, and crustaceans," to read better.

It also clears up ambiguity that happens with non-serial comma lists, as demonstrated in this excellent example I found on another site: "I'd like to thank my parents, Ayn Rand and God."

I'd just like to add to Your Mother's fine comments on the subject. The idea of dropping the comma before "and" in lists of more than 2 items was popularized by newspapers motivated by cutting costs to increase profits. Although the professional writers and editors of newspapers have been sources of some fine guidance in the art of writing, they quite simply got this one wrong.

Some respected producers of style guides have previously adopted this no-comma rule because it came from a respected source (professional writers). Other respected producers of style guides have tried to stradle the fence and say that such a comma is optional but should be used when it makes the meaning clearer. But this latter stance only allows for the removal of ambiguity in one direction, not allowing the absense of the comma to convey any meaning.

So you really should only drop this comma if you feel that you are saving more in ink/paper/bits than you are losing in power and clarity of expression. For me, the exchange rates among these currencies makes that decision effortless.

I'd be interested in well-reasoned arguments for the eliding of this comma. The only ones I've heard to date fit in with our most recent poll topic, such as "Appeal to Authority" or "Appeal to Popularity".

sub serial {
    join(', ', @_[0 .. $#_-1])
    . (@_ > 2 ? ',' : '')
    . (@_ > 1 ? ' and ' : '')
    . $_[-1];
}
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sub serial {
    my $last = pop;
    join(', ', @_)
    . (@_ > 1 ? ',' : '')
    . (@_ > 0 ? ' and ' : '')
    . $last;
}
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Makeshifts last the longest.

I agree cleaner with pop, but to many ternary operators. :)

sub serial {
    my $last = pop;
    @_ ? join(', ', @_) . " and $last" 
       : $last;
}
[download]

update:forgot about that whole, if there are more than two in the list with the commas bit, so neglect the above as it does not do what the original code posted does (as Aristotle's does.)

-enlil

I was actually about to reply with something similar myself before I noticed there's three cases to distinguish. FWIW, here's my previous take - which adds a comma even when there's only two elements in the list:

sub serial {
    my $last = '';
    ($last, $_[-1]) = ($_[-1], 'and ') if @_ > 1;

    join(', ', @_) . $last;
}
[download]

Makeshifts last the longest.

sub serial {
    my $last = pop;
    my $seclast = pop;
    $seclast .= ',' if @_;
    join('', map "$_, ", @_) . join(' and ', $seclast || (), $last);
}
[download]

Makeshifts last the longest.

nice. i'll put an adendum in about the prototype not being needed; or just kill it and put a note in about that instead.

Yes, nice, except it doesn't work as specified. *grumble* It doesn't add an extra comma for lists of more than two elements. I don't know where I had my eyes (or my brain, for that matter) when I was testing it.

Makeshifts last the longest.