Parrot virtual machine

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Parrot virtual machine

Final release	8.1.0 / February 16, 2016; 8 years ago (2016-02-16)[1]
Repository	github.com/parrot/parrot
Written in	Cross-platform
Successor	MoarVM (for Raku)
Type	Virtual machine
License	Artistic License 2.0
Website	www.parrot.org

Parrot is a discontinued

The Parrot Foundation was dissolved in 2014.[7] The Foundation was created in 2008 to hold the copyright and trademarks of the Parrot project, to help drive development of language implementations and the core codebase, to provide a base for growing the Parrot community, and to reach out to other language communities.^[8]

Historical design decisions are documented in the form of Parrot Design Documents, or PDDs, in the Parrot repository.^[9]

Until late 2005, Dan Sugalski was the lead designer and chief architect of Parrot. Chip Salzenberg, a longtime Perl, Linux kernel, and C++ hacker, took over until mid-2006, when he became the lead developer. Allison Randal, the lead developer of Punie and chief architect of Parrot's compiler tools, was the chief architect until mid-October 2010 when she stepped down and chose Christoph Otto as the new chief architect.^[10]

The goal of the Parrot virtual machine was to host client languages and allow inter-operation between them. Several hurdles exist in accomplishing this goal, in particular the difficulty of mapping high-level concepts, data, and data structures between languages.

The differing properties of

Parrot provides a suite of compiler-writing tools^[11] which includes the Parser Grammar Engine (PGE), a hybrid parser-generator that can express a recursive descent parser as well as an operator-precedence parser, allowing free transition between the two in a single grammar. The PGE feeds into the Tree Grammar Engine (TGE) which further transforms the parse-tree generated by PGE for optimization and ultimately for code generation.

The most complete language implementations targeting the Parrot VM were Raku (known at the time as Rakudo Perl 6), Lua and a new language called "Winxed".^[12] Projects to implement many other languages were started, including PHP, Python, and Ruby; along with esoteric and demonstration languages such as Befunge and the "squaak" tutorial language.^[13] None of these projects were successful in becoming the primary implementation of their respective languages.^[4]

There are three forms of program code for Parrot:

• Bytecode^[14] is binary and is natively interpreted by Parrot. Bytecode is usually stored in files with the filename extension ".pbc".
• Parrot assembly language (PASM) is the low level language that compiles down to bytecode. PASM code is usually stored in files with the filename extension ".pasm".
• Parrot intermediate representation (PIR^[15]) is a slightly higher level language than PASM and also compiles down to bytecode. It is the primary target of language implementations. PIR transparently manages Parrot's inter-routine calling conventions, provides improved syntax, register allocation, and more. PIR code is usually stored in files with the filename extension ".pir".

Parrot is register-based like most hardware CPUs, and unlike most virtual machines, which are stack-based. Parrot provides four types of registers:

• I: native integer type
• N: floating-point numbers
• S: advanced string registers with Unicode support
• P: PMC, or Polymorphic Container — Parrot object type

Parrot provides an arbitrary number of registers; this number is fixed at compile time per subroutine.

In PASM

    set I1, 4
    inc I1        # I1 is now 5
    add I1, 2     # I1 is now 7
    set N1, 42.0
    dec N1        # N1 is now 41.0
    sub N1, 2.0   # N1 is now 39.0
    print I1
    print ', '
    print N1
    print "\n"
    end

In PIR

 .sub 'main' :main
    $I1 = 4
    inc $I1     # $I1 is now 5
    $I1 += 2    # $I1 is now 7
    $N1 = 42.0
    dec $N1     # $N1 is now 41.0
    $N1 -= 2.0  # $N1 now 39.0
    print $I1
    print ', '
    print $N1
    print "\n"
 .end

mod_parrot is an optional module for the Apache web server. It embeds a Parrot virtual machine interpreter into the Apache server and provides access to the Apache API to allow handlers to be written in Parrot assembly language, or any high-level language targeted to Parrot.

• MoarVM
• GraalVM
• Common Language Runtime (CLR)
• Comparison of application virtual machines
• Da Vinci Machine

• Official website
• Perl 6 and Parrot links
• For mod_parrot:
  • "Mod_parrot website". parrot.org. Jeff Horwitz. Retrieved 2023-08-18.
  • Horwitz, Jeff (December 22, 2004). "Introducing mod_parrot". perl.com. O'Reilly Media.
  • Josh McAdams (June 3, 2008). "Jeff Horwitz on mod_parrot". Perlcast. Perlcast.com. Archived from the original on 2008-09-07. Retrieved 2008-06-09.