On Fri, Aug 20, 2004 at 10:49:17AM -0600, Luke Palmer wrote:
:
: method postcircumfix:<> ($self: *%opt) returns List {
: scalar $self.<*%opt>, $self.<*%opt> # [1]
: }
:
: [1] Look, Larry, I had to use C<scalar>! Maybe we _do_ need to revive
: $()!
It's not clear to me that $() would have made this more readable...
I think if we ever come up with a single-character unary scalar
operator, it should be something other than '$'. I just don't like
the look of '$($', nor the fact that the inner $ is doing something
quite different from the outside one.
Maybe we could resurrect the '_' operator to mean scalar() at the
symbolic unary precedence level. Underline looks sufficiently
different from $. Your example would then be:
method postcircumfix:<> ($self: *%opt) returns List {
_$self.<*%opt>, $self.<*%opt> # [1]
}
Then I suppose binary _ would be defined as:
$a _ $b
is the same as
_($a, $b)
which is the same as
[$a, $b]
Not clear what $a _ $b _ $c would mean though...
Hmm. There's another possibility. We just got through explaining how
the => binary operator imposes scalar on its right side. There's no
corresponding unary operator. So we could make one:
method postcircumfix:<> ($self: *%opt) returns List {
=>$self.<*%opt>, $self.<*%opt> # [1]
}
then the definition of binary => is already obvious. On the other
hand, unary =>$x probably ought to mean $_ => $x or some such (where
"some such" includes "nothing at all"). And I'd prefer to keep all
the symbolic unaries single chars. So I lean towards _.
But something is tickling the back of my mind as a different proposed
meaning for bare _ as a token, and I can't remember what. Placeholders
for anonymous unification, a la Prolog, maybe. Whatever it is, it
could probably coexist with _ as a unary, much like we're thinking
of making unary * coexist with a splat slice in a multidimensional
subscript.
Since _ would primarily be used as a unary, it wouldn't suffer as
much from ambiguity as when it was proposed for string concat, where
$a_$b would be a syntax error. It would be a problem for functions
calls, however:
push @x, _ myfunc();
But really, that's no more characters than:
push @x, =>myfunc();
I don't see any other single-character candidates. It's probably
time to do an exhaustive check again. First of all, none of the
alphabetic ones are any better than underscore, except possibly
for mnemonic value. Unfortunately, the only obvious one, 's', is
taken. That leaves punctuation. Here's what my keyboard offers
in ASCII:
say `myfunc(); # taken
say ~myfunc(); # taken
say !myfunc(); # taken
say @myfunc(); # taken
say #myfunc(); # taken
say $myfunc(); # taken
say %myfunc(); # taken
say ^myfunc(); # possible, but easily confused with +^
say &myfunc(); # taken
say *myfunc(); # taken
say (myfunc(); # taken
say )myfunc(); # pragmatically impossible (breaks bracket matching)
say -myfunc(); # taken
say _myfunc(); # indentifer character in C culture
say +myfunc(); # taken
say =myfunc(); # visually and semantically confusing
say [myfunc(); # taken
say ]myfunc(); # pragmatically impossible (breaks bracket matching)
say {myfunc(); # taken (and then taken some more)
say }myfunc(); # pragmatically impossible (breaks bracket matching)
say \myfunc(); # taken
say |myfunc(); # visually and semantically confusing
say ;myfunc(); # too important as expression stopper: loop ;; {...}
say :myfunc(); # taken
say 'myfunc(); # taken
say "myfunc(); # taken
say ,myfunc(); # visually and semantically confusing
say <myfunc(); # taken, probably
say .myfunc(); # taken
say >myfunc(); # visually and semantically confusing
say /myfunc(); # taken
say ?myfunc(); # taken
If we're willing to take the Latin-1 hit, then we also have these
punctuational possibilities:
¡ 00A1 INVERTED EXCLAMATION MARK
¢ 00A2 CENT SIGN
£ 00A3 POUND SIGN
¤ 00A4 CURRENCY SIGN
¥ 00A5 YEN SIGN
¦ 00A6 BROKEN BAR
§ 00A7 SECTION SIGN
¨ 00A8 DIAERESIS
© 00A9 COPYRIGHT SIGN
ª 00AA FEMININE ORDINAL INDICATOR
« 00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
¬ 00AC NOT SIGN
00AD SOFT HYPHEN
® 00AE REGISTERED SIGN
¯ 00AF MACRON
° 00B0 DEGREE SIGN
± 00B1 PLUS-MINUS SIGN
² 00B2 SUPERSCRIPT TWO
³ 00B3 SUPERSCRIPT THREE
´ 00B4 ACUTE ACCENT
µ 00B5 MICRO SIGN
¶ 00B6 PILCROW SIGN
· 00B7 MIDDLE DOT
¸ 00B8 CEDILLA
¹ 00B9 SUPERSCRIPT ONE
º 00BA MASCULINE ORDINAL INDICATOR
» 00BB RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
¼ 00BC VULGAR FRACTION ONE QUARTER
½ 00BD VULGAR FRACTION ONE HALF
¾ 00BE VULGAR FRACTION THREE QUARTERS
¿ 00BF INVERTED QUESTION MARK
× 00D7 MULTIPLICATION SIGN
÷ 00F7 DIVISION SIGN
Of those, only
say ¢myfunc();
say §myfunc();
strike me as both sufficiently mnemonic and sufficiently visible. Of
the two I think I prefer the section sign.
But overall I think I still prefer _ to anything else. For the moment...
Larry
