Perl 6
SMOP: Revision 82

Simple Meta Object Programming / Simple Matter Of Programming

If you want to help SMOP, you can just take on one of the lowlevel S1P implementations and write it. If you have any questions ask ruoso at #perl6 @, as your second choice you can ask pmurias at #perl6 @

The Slides for the talk Perl 6 is just a SMOP are available, it introduces a bit of the reasoning behind SMOP.

SMOP is an alternative implementation of a C engine to run Perl 6. It is focused in getting the most pragmatic approach possible, but still focusing in being able to support all Perl 6 features. Its core resembles Perl 5 in some ways, and it differs from Parrot in many ways, including the fact that SMOP is not a Virtual Machine. SMOP is simply a runtime engine that happens to have a interpreter run loop.

The main difference between SMOP and Parrot (besides the not-being-a-vm thing), is that SMOP is from bottom-up an implementation of the Perl 6 OO features, in a way that SMOP should be able to do a full bootstrap of the Perl 6 type system. Parrot on the other hand have a much more static low-level implementation (the PMC).

The second most important difference is that SMOP doesn't have any kind of bytecode generation/interpretation. SMOP will probably traverse something that looks a lot more an AST then some assembly language. This also allows easy integration with other runloops.

The same way PGE is a project on top of Parrot, SMOP will need a grammar engine for itself. KindaPerl6 is one that is designed with portability in mind, so it should be easy to just implement a KP6 backend to emit C code that uses the SMOP runtime to then bootstrap the grammar engine in SMOP itself.

SMOP already uses KP6 to parse the "stage 0" language that is used to build the SMOP execution frames, and it should be also used to compile the "stage 1" language, as soon as SMOP
has some more features in its runtime.

SMOP is the implementation that is stressing the meta object protocol more than any other implementation, and so far that has been a very fruitful exercise, with Larry making many clarifications on the object system thanks to SMOP.

Important topics on SMOP

  • SMOP doesn't recurse in the C stack, and it doesn't actually define a mandatory paradigm (stack-based or register-based). SMOP has a Polymorphic Eval, that allows you to switch from one interpreter loop to another using Continuation Passing Style. See SMOP Stackless.
  • SMOP doesn't define a object system in its own. The only thing it defines is the concept of SMOP Responder Interface, which then encapsulates whatever object system. This feature is fundamental to implement the SMOP Native Types.
  • SMOP is intended to bootstrap itself from the low-level to the high-level. This is achieved by the fact that everything in SMOP is an Object. This way, even the low-level objects can be exposed to the high level runtime. See SMOP OO Bootstrap.
  • SMOP won't implement a parser in its own, it will use KindaPerl6 parser or whatever parser gets ported to its runtime first.
  • SMOP defines two Domain Specific Languages for low-level aid:
  • In order to enable the bootstrap, the runtime have a set of SMOP Constant Identifiers that are available for the sub-language compilers to use.
  • There are some special SMOP Values Not Subject to Garbage Collection.

Other matters

SMOP Development ROADMAP

In order to keep this simple, the ROADMAP will stay here and will be edited as needed.

S1P - Read it "Swamp"

  • x.x.x - Low-level Code implementation
  • 0.2.3 - Low-level Attribute implementation
  • 0.2.4 - Low-level Package implementation
  • 0.2.5 - Low-level SubMethod implementation
  • 0.2.6 - Low-level Signature implementation
  • 0.2.7 - Default MetaClass implementation (This is the default Perl 6 OO Meta Class)
  • 0.2.8 - s1p compiler
  • 0.2.9 - src-s1p/ compiled to src-s1p/Object.c
  • 0.2.10 - Final review on the s1p language
  • 0.2.11 - working
  • 0.3.0 - Object with all features working

Completing SMOP runtime

  • 0.3.1 - SMOP NATIVE prototypes and lowlevel operators
  • 0.3.2 - Undef builtin types.
  • 0.3.3 - Immutable builtin types.
  • 0.3.4 - Mutable builtin types.
  • 0.4.0 - Lexical Scope / Namespaces.

Perl 6 SMOP

  • 0.5.0 - STD AST types.
  • 0.6.0 - STD AST -> runtime frames (real interpreter)
  • 0.7.0 - STD SMOP backend
  • 1.0.0 - STD bootstraps in SMOP

Other Features

  • x.x.x - perl5 embedded - libperl
  • x.x.x - parrot embedded - libparrot
  • x.x.x - python embedded (stackless python?)
  • x.x.x - jvm embedded - libgcj
  • x.x.x - spidermonkey embedded - libmoz-js

SMOP Changelog

Usually, things from ROADMAP should come to here when its done.

2008-07-25 - PaweĊ‚ Murias

  • x.x.x - Low-level Array implementation
  • x.x.x - Low-level Hash implementation

2008-07-25 - Daniel Ruoso

  • 0.2.2 - p6opaque Responder Interface (This is the default Perl 6 OO Responder Interface)

2008-07-24 - Daniel Ruoso

  • x.x.x - p6opaque refactoring almost finished. After much debate the final p6opaque format is documented in SMOP p6opaque Implementation. Metaclass delegation is already working again. Now p6opaque uses directly Scalars, Hashes and Arrays instead of a lowlevel implementation of that. This is indeed much simpler (pmurias++ for pushing in that direction)
  • x.x.x - ___NATIVE_CAPTURE_ONLY___, ___CONST_IDENTIFIER_ONLY___ and ___INVOCANT_RI_SHOULD_MATCH___ are C macros that do some sanity checking on the lowlevel invocation.
  • x.x.x - p6opaque_proto_storage completed!
  • x.x.x - accessor for every member of p6opaque implemented.

2008-07-18 - Daniel Ruoso

  • x.x.x - Define yet another phase into the boot sequence for things that need a interpreter instance
  • x.x.x - interpreter.goto(bool) means "release the current continuation"

2008-07-16 - Daniel Ruoso

  • x.x.x - $p6opaque.^!methods.push($method) calls $p6opaque.^!methods.register($identifier, $signature, $method), fetching the information from the method object.

2008-07-15 - Daniel Ruoso

  • x.x.x - all tests valgrind-clean again. test/14 still missing the two functions.

2008-07-11 - Daniel Ruoso

  • x.x.x - $p6opaque.^!methods() working, it returns a proxy object that will introspect inside the p6opaque. test/14 still with memory leaks.

2008-07-10 - Daniel Ruoso

  • x.x.x - tests revised after some sm0p changes. test/14 is written and compiles, but it still fails the tests.

2008-07-09 - Daniel Ruoso

  • x.x.x - lowlevel method uses the new signature for "call". This is important for the test/14 still in development.

2008-07-08 - Daniel Ruoso

  • x.x.x - smop_lowlevel only uses capture-less DESTROYALL call for a few selected types.

2008-07-04 - Daniel Ruoso

  • x.x.x - p6opaque successfully delegates the calls to the metaclass (valgrind-clean)

2008-03-11 - Daniel Ruoso

  • x.x.x - Low-level Scalar implementation

2008-02-22 - Daniel Ruoso

  • 0.2.1 - Low-level Method implementation (this is not the standard Method type, just something that complies to the API)

2008-02-14 - Daniel Ruoso

  • x.x.x - Runtime creation of constant identifiers

2008-02-05 - Daniel Ruoso

  • FIRST MAJOR MILESTONE ACHIEVED: sm0p - Lame Default SMOP Interpreter Implementation
  • 0.2.0 - Final review on SMOP REFERENCE and RELEASE Policy and code revision for memory leaks.

2008-02-01 - Daniel Ruoso

  • 0.1.4 - Final review on Continuation Passing Style implementation

2008-01-31 - Daniel Ruoso

  • 0.1.3 - sm0p preprocessor
  • x.x.x - Several bug fixes in the capture and in slime.
  • x.x.x - 02_stack.t does ok 1..4 for the first time, this means that sm0p is interpreted correctly

2008-01-24 - Daniel Ruoso

  • x.x.x - Automake prepared to run the sm0p preprocessor.
  • 0.1.2 - SMOP SLIME prototypes and lowlevel operators
  • x.x.x - SMOP__SLIME__Capturize
  • x.x.x - SMOP__SLIME__Node
  • x.x.x - native int type
  • x.x.x - SMOP__SLIME__CurrentFrame

2008-01-23 - Daniel Ruoso

  • x.x.x - SMOP__SLIME__Frame first code
  • x.x.x - native bool type

2008-01-21 - Daniel Ruoso

  • 0.1.1 - Capture type (lowlevel implementation)

2008-01-18 - Daniel Ruoso

  • 0.1.0 - Port YAP6__CORE__Value code to SMOP__Object code.
  • 0.x.x.x - "Identifier Name Constant" type and the definition of the pool of constants.

See also the Old YAP6 Changelog.

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