On Mon, 15 Jul 2002, Luke Palmer wrote: > On Mon, 15 Jul 2002, Karl Glazebrook wrote: > > > @solution = (^-@b + sqrt(@b^**2 ^+ 4^*@a^*@c) ) ^/ (2^*@a); > > That would not be very pretty, indeed. It would also not be very > efficient. (BTW, its b**2 - 4ac, not + :) A more efficient, pretty, > and clear way would be like this:
Not necessarily true! The compiler can figure out that a sequence of operators is hyped and avoid the temporary arrays (like your for-loop). It takes a little more work, but it's really not all that hairy when the necessary information is right in the syntax. Furthermore, the beauty of the hyper-operators (or the implicitly-vector normal operators below) is they don't give the programmer a loop body in which to do wierd things to the arrays. Since @y = $a ^* @x ^+ @b is all a single operation from the user's perspective, the compiler can make it faster than a loop written in pure Perl. > > What is wrong with using @a * @b - the only reason I can think is to > > preserve > > a backward compatibility which is not needed? > > ... > > Why do we need to preserve @x as array length when you are proposing > > @x.length ? > > I see your point. I went through a couple of my larger perl programs, and > the only time I used arrays in numeric context was in the C-style for > loop. I actually find myself using @a in numeric context quite a bit, but would have no objections to changing it to @a.length, since the former is completely bizarre to someone not familiar with Perl. > I wouldn't mind if this proposal was accepted, but I also think the hyper > operator syntax is nice. At least for what I'm doing, in which it's > usually Yet Another shorthand for a C<foreach> (or now just C<for>) loop. Maybe we could add a hyper-context to cut down on the line-noise without startling Perl 5 programmers: @solution = ^( -@b + sqrt(@b**2 + 4*@a*@c) ) / (2*@a) ); Or (this might break something): @solution ^= -@b + sqrt(@b**2 + 4*@a*@c) ) / (2*@a); (then watch as people have all their inplace-array-bitwise-xors change meaning;) I agree that the ^op syntax is painful if you have to type it a lot, but for the majority of people not using Perl for numerical code, hyper-operation is something out of the ordinary, and seems to deserve syntactic markers. For example: my @things = @args || @defaults; # @args if it is true, else @defaults # vs my @things = @args ^|| @defaults; # $args[$_] || $defaults[$_] for 0..X If infix operators are implicitly vector, the first's becoming the second could be a bit surprising. Even more so since, if we're handling infinite lists, hyper-operators should iterate over the number of items in their shorter argument. /s
