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Postings from February 2002
Re: Mono and Perl6....
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From:
Paolo Molaro
Date:
February 7, 2002 08:10
Subject:
Re: Mono and Perl6....
Message ID:
20020207161003.GB636@debian.org
On 02/06/02 Larry Wall wrote:
> Black pots and kettles aside, they bring up a lot of interesting issues
> that we have to think about if we're going to be more language-neutral
> than the CLR.
The main issue is that there is a point where too much generality
will make the VM too hard to target code for. One could develop a VM
that uses the nice sparc instruction set, but writing compilers for it
would be too hard, that's why many languages are interpreted, because
generating machine instructions is hard (even when you target a single
instruction set). Yes, portability is an issue, too, but if that was
the case, we'd have jitters for perl/python/ruby/whatever for the main
cpus for a long time.
A VM will always favour a particular language (hey, cpus favour C over
perl, for example:-). The CLR favours IL _and_ C# (there are many
features in the CLR not used by C#), but it has enough features that
make it easier for a lot of languages to target it (function pointers,
tail recursion, alloca to name a few).
Some languages will need more work to port to the CLR than C# and for
sure a Perl on CLR method invocation will be slower than a C# method
invocation, but that is true on todays systems as well:-)
There is a difference from a VM that makes supporting any langauge hard
and a VM that makes it hard only for a few. A VM that supports all
the languages on the same foot means that it supports all of them badly:-)
How will method invocation work on the parrot VM? You'll need a
invoke() vtable slot that does all the magic and guess what, you'll need
to do the same if you target the CLR.
Currently it's not clear how much advantage a parrot VM could give
over a VM like the CLR, but I guess we'll see that only when perl 6
will use it.
lupus
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