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Parrot 0.1.1 'Poicephalus' Released
Pan T. Hose writes "The long awaited release of Parrot 0.1.1 "Poicephalus" has been finally announced on perl.perl6.internals newsgroup and perl6-internals mailing list simultaneously by Leopold Toetsch followed by an announcement on use Perl by Will Coleda and now also on Slashdot." (Read on for a list of changes since the last release, as well as a number of useful links.)
Pan T. Hose continues "The most important changes since the previous version 0.1.0 (code-named 'Leaping Kakapo' and
released in February) are:
- Python support: Parrot runs 4/7 of the pie-thon test suite
- Better OS support: more platforms, compilers, OS functions
- Improved PIR syntax for method calls and <op>= assignment
- Dynamic loading reworked including a "make install" target
- MMD - multi method dispatch for binary vtable methods
- Library improvement and cleanup
- BigInt, Complex, *Array, Slice, Enumerate, None PMC classes
- IA64 and hppa JIT support
- Tons of fixes, improvements, new tests, and documentation updates
from the faq:
Parrot is the new interpreter being designed from scratch to support the upcoming Perl6 language. It is being designed as a standalone virtual machine that can be used to execute bytecode compiled dynamic languages such as Perl6, but also Perl5. Ideally, Parrot can be used to support other dynamic, bytecode-compiled languages such as Python, Ruby and Tcl.
There are 10 kinds of people: Those that understand ternary; those that don't; and those that don't care.
Performance.
.NET VM didn't even exist when we started development, or at least we didn't know about it when we were working on the design. We do now, though it's still not suitable.
.NET back ends.
From the FAQ:
Why your own virtual machine? Why not compile to JVM/.NET?
Those VMs are designed for statically typed languages. That's fine, since Java, C#, and lots of other languages are statically typed. Perl isn't. For a variety of reasons, it means that Perl would run more slowly there than on an interpreter geared towards dynamic languages.
The
So you won't run on JVM/.NET?
Sure we will. They're just not our first target. We build our own interpreter/VM, then when that's working we start in on the JVM and/or
My UID is the product of 2 primes.
That's not what it is. Perl and Python (and most "major" interpreted languages, I would suspect), first compile the script to byte-code, then execute the byte-code in a VM.
.Net VM. .Net for two reasons: .Net didn't exist when they began :) .Net is designed for compiled languages (C++, C#, VB, etc), and supposedly that would cause a performance hit over a VM designed for interpreted languages. (Plus, it's not designed to be portable, like Parrot is)
At some point along the line, someone said "Hey! Why are we writting VMs for every single language? They all do pretty much the same thing!".
So Parrot is that, a common VM. Perl6 compiles to Parrot bytecode, instead of the perl-only-bytecode it was using for Perl5.
Since that bytecode format is open, and the VM free, any other interpreted (or compiled, I guess) language (Python, Ruby, TCL, LUA, whatever) can make their compilers output Parrot bytecode.
That way they don't have to build and maintain their own VM, and they get the benefits of future optimizations to Parrot.
For example, I could write a just-in-time compiler for Parrot for my favorite platform, and every Parrot-enabled language could take advantage of that.
Doing that now, I'd have to pick a language to optimize. Do I want to make Python faster? Or Perl?
Python is going to use it in the future,last I heard. (probably as another backend like Jython or IronPython, not as a replacement for CPython)
I think they were waiting on the byte-code format stabilizing.
All in all, it's a very cool idea. Makes it a hell of a lot easier for people to make new interpreted languages, since they only have to target Parrot, and they've got a mature, debugged, VM that runs on multiple platforms. (in theory, at least. I don't think it's there yet)
It's not that similar to the JavaVM (which is only designed to run Java, not a pile of different languages), but it is kinda like the
The developers of Parrot created Parrot instead of targeting
1.
2.
I respond to your sigs
As it said, Python, Perl, Ruby, Smalltalk, Lisp, and most of the languages targeted by Parrot are dynamically typed and have dynamic message passing (method calls). This means that typechecking is done by the run-time environment, not by the compiler. Likewise, it is not known untill runtime which if an object has a method. Therefore, the runtime has to do a fair amount of checking (mostly symbol table lookups). If you were to do this with a VM designed for static languages (JVM, .NET) that do not do this checking for you, then you would have to implement all of it as byte-code in the VM - in effect you would be writing a big chunk of a Perl interpretor in Java.
This approach would inevitably be slower than the existing Perl 5 interpretor, while the Parrot approach has managed to be significatly faster than the current Perl 5 interpretor. The reasons are that 1) all of the runtime checking is highly optimized native code 2) after the complex perl code is translated into a simpler form, the traditional compiler optimizations can be applied to the code.
I think he means register based.
From one of the examples, we get:
set I1, 1
set N1, 4.2
set S1, "Resting"
print I1
print ", "
print N1
print ", "
print S1
print "\n"
end
Which seems to indicate a heavy use of register type functionality. This will map to hardware (thusly faster) better, much more so than a stack based (java) VM implementation. Especially for dynamically typed languages (perl, python, ruby, etc).
The point of that is also that you have only one debugged runtime and don't have to write your own for each language.
A very important fact hasn't been mentioned here: When you compile multiple languages to the same VM, you don't automatically get interoperatibility between those languages. Interoperatibility is a different concept that must be separately achieved, mostly by defining additional rules and standards on-top-of the VM specification.
For example, look at different C or C++ compilers on Linux/x86. They all compile to the same machine code, but Intel machine code has no concept of "symbol names", "class names", "type names" etc., so, for the compiled codes to be interoperable, they must comply to additional specifications like ELF or some C++ ABI ("name mangling").
Parrot bytecode may define some or all of those concepts, but some scripting languages will probably define additional features (macros, MI, continuations etc.) that have no "native" representation in Parrot, so additional conventions to represent those things in Parrot must be agreed upon. The .NET CLS ("common language specification") is another example of such a set of addional rules to provide for language interoperatibility.
This is NOT a strong vs weak typing thing. This is a static vs dynamic typing thing. The strength of a type system has no relation to when it's enforced.
You can have all combinations: