Quoted from "Seven Deadly Sins of Introductory Programming Language
Design" [1] by Linda McIver and Damian Conway:
We have shown over one thousand novice programming students
the C/C++ expression:
"the quick brown fox" + "jumps over the lazy dog"
and asked them what they believe the effect of the + sign is.
Not one of them has ever suggested that the + sign is illegally
attempting to add the address of the locations of the first two
characters of the two literal strings. Without exception they
believed that the + should concatenate the two strings.
Makes perfect sense to me.
Can we overload + in Perl 6 to work as both numeric addition
and string concatenation, depending on the type of the operand
on the left?
I realise the answer is "probably not", given the number/string
ambiguity of Perl variables:
my $a = 123;
my $b = 456;
$a + $b; # 579 or 123456?
I quite like '_' as the string concatenation operator (so much so
that I added it to the Template Toolkit some time ago, confidently
telling people that it's what Perl 6 would use :-). It ties in
nicely with the 123_456 numerical style.
On the other hand, I'm not a big fan of using '~' to indicate
string context. The tilde (aka wobbly operator) seems much better
suited to smart matching, IMHO, being reminiscent of the "almost
equal to" operator (which I would attempt to include here if I
had the slightest clue how to make my keyboard speak Unicode).
Another option: could we quote operators to indicate string context?
$a "+" $b
This would tie in nicely with using [ ] to indicate vectorised
operators, although I realise that particular syntax has been
disvogued of late.
@a [+] @b
A
[1] http://www.csse.monash.edu.au/~damian/papers/ [2]
[2] Good paper, well worth a read. That Conway chap seems to know
his cookies. His name rings a bell, too...
