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Re^7: what would you like to see in perl5.12?

by BrowserUk (Patriarch)
on Aug 10, 2008 at 04:59 UTC ( [id://703376]=note: print w/replies, xml ) Need Help??

in reply to Re^6: what would you like to see in perl5.12?
in thread what would you like to see in perl5.12?

Sorry if I missed the correspondence between Perl6::Declare and Devel::Declare & Perl6::Signatures. If indeed there is any?

Perl6::Declare lets you declare subroutine/methods using Perl 6 signatures, which are lovely. I heard this turns out to actually be faster than Perl 5 calling conventions,

Devel::Declare talks about "declarator magic" and Perl6::Signature contains a Parse::RecDescent-based parser for signatures.".

If anything that uses P::RD turns out to be faster than my( $x, $y, $z ) = @_;, it will indeed be "magic". Oh! and I'll eat my hat! (I'll have to buy a hat to eat, but I'm sure I can find something tasty at a thrift shop:)

To clarify, what I meant by my request for less overhead, was a reduction in the internal (C-level) overhead associated with calling a perl subroutine, that results in this kind of comparison of similar subroutines coded in Perl and another bytecode compiled, interpreted language: Java.

Are Perl's function calls slow?

The archetypal test of function call performance is the Ackermann Function. Go here to see the list of other languages that out-perform Perl for function call performance. Many of those are fully pre-compiled languages. Many are not.

For comparison purposes, look at straight forward implementations in Perl, with the same in Java.


P:\test\MJD>ack1 9 Ack(3,9): 4093 78.843 83.671 0 0


P:\test\MJD>timethis "c:javac && java ackermann 9" TimeThis : Command Line : c:javac && java ackermann 9 TimeThis : Start Time : Fri Sep 02 22:01:28 2005 Ack(3,9): 4093 TimeThis : Command Line : c:javac && java ackermann 9 TimeThis : Start Time : Fri Sep 02 22:01:28 2005 TimeThis : End Time : Fri Sep 02 22:01:29 2005 TimeThis : Elapsed Time : 00:00:01.031

I've included the compilation and runtime for Java to even the score a little. JIT was not enabled.

So 83.6 seconds for Perl, and 1.031 seconds for Java!

Conclusion: Perl's function calls are slow.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

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Re^8: what would you like to see in perl5.12?
by gaal (Parson) on Aug 10, 2008 at 20:53 UTC
    Devel::Declare lets you hook into the perl parser and create your own bits of syntax. It's a little bit like a source filter, except more magical with all the good, bad, and ugly that can entail.

    Perl6::Signature's being P::RD-based is not material here. Once per function, at parse time, Perl6::Declare will parse the Perl 6 signature of a sub and install data binding (and possibly, runtime checks) as appropriate.

    The speed comes from another module (sorry to keep calling rabbits out of hats, those aren't the ones anyone gets to eat). It's Data::Bind, which too lacks documentation except for its tests. Word is it's in some cases faster than = @_.

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