On Wednesday 05 May 2010 10:25:48 Craig DeForest wrote:
> Jarle,
> 
> Neat stuff.
> 
> The PDL/IDL split has been known anecdotally for a long time -- the PP
> engine really does well at generating vector code, and RSI have long
> touted the efficiency of IDL vector code. Both languages are probably
> RAM bound and not significantly different in speed when they are
> inside large(r than cache) vector operations.
> 
> IDL's interpreter, on the other hand, really blows chunks compared to
> Perl's.  It's not legally possible to know what IDL is doing, but I
> suspect it merely tokenizes, rather than JIT-compiling, the
> interpreted code, so the interpreter has to do a lot more work at run-
> time (work that Perl caches up-front).

Just a nitpick - perl 5 does not do JIT-compilation either. In JIT compilation 
one converts the internal bytecode (also called P-code) to machine language at 
run-time so it will later execute faster. That's what the JVM and the .NET CLR 
are doing, but perl 5 (the Perl 5 implementation) does not do it, at least not 
yet. See:

* http://en.wikipedia.org/wiki/P-code_machine

* http://en.wikipedia.org/wiki/Just-in-time_compilation

> 
> The python curve is (as Daniel pointed out) surprising - folks in my
> office keep advocating switching to Python, largely because it is
> alleged to be screamingly fast.  I'm not enough of a python guy to
> know if there are simple optimizations that are being ignored...
> 

Well, the common belief is that the default CPython implementation (which most 
people are using) is roughly as fast as perl 5 is, with various benchmarks 
being somewhat in favour of this or the other, but usually not a very dramatic 
difference. This is while ruby-1.8.x is much slower than both. On the other 
hand, Python has many alternative implementations: Jython (for the JVM), 
IronPython (for .NET), Psycho, stackless Python, etc. and some of them may 
perform better than CPython. As a result, I'm not sure of the origin of 
Python's alleged reputation of being "screamingly fast" and what is the grain 
of truth in it.

Regards,

        Shlomi Fish

> Cheers,
> Craig
> 

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