PIR and PASM are both very low-level languages by any programming standards, even though they support some important features of high-level dynamic languages,and PIR has some symbolic syntax features. Important re-occurring programming tasks in these languages have been extracted out into a series of runtime libraries to help make these tasks easier. Libraries written in PIR or PASM can be easily included and used from any of the high-level language compilers that target Parrot, in addition to being used in the Parrot test suite and PIR/PASM code generators like PCT.
Some modules, such as pcre.pir and postgres.pir are NCI wrappers for common compiled shared libraries.
From the Parrot repository, there are a number of premade libraries in runtime/library/, and several generated libraries in runtime/include that can be used by Parrot hackers and HLL-implementers alike, if needed. This chapter is going to give a brief overview of some of these libraries and how they are used.
Libraries are precompiled code files that can be loaded into Parrot.
There are ways to load a library into Parrot,
each with a slightly different mechanism.
.loadlib PIR directive causes the library file to be loaded at compile-time.
load_lib opcode causes the library to be loaded dynamically at runtime.
Config.fpmc is generated during the build process.
The file defines a hash PMC that contains information about the system where Parrot was built.
By accessing the data in this PMC,
you can determine how Parrot was compiled and what features and libraries it has available.
Since the Parrot project started as the internals of the Perl 6 development project, and since a number of Perl hackers are very active in Parrot, several libraries in the Parrot runtime are based on common Perl 5 libraries.
Perl 5 had
that would print out the complete contents and structure of any arbitrary complex data type.
This is useful in a number of cases,
with debugging not the least of them.
It's good to verify that complicated nested data structures are being composed and accessed in the manner that the programmer intends.
Parrot does not intend to reinvent any wheels, and there is lots of important functionality encapsulated in various libraries that Parrot does not copy. Instead of having to reimplement all sorts of libraries for Parrot, Parrot provides the NCI interface to work with these libraries directly. PIR or PASM wrapper libraries are provided to create an interface that programs running on Parrot can use to access functionality in these libraries.
Notice that these libraries are depending on having the compiled libraries they reference already installed on your system. Many of these are detected during the configuration process. If you do not have these libraries installed, you cannot call the modules discussed here. We will give some information about how to find and install the libraries, however.
Notice that this is only a partial list of wrapper libraries that come bundled with the Parrot repository. Additional library wrappers may be added to the repository at a later date, or may be available from other sources.
PCRE is a library that implements regular expressions using Perl 5 syntax.
NCurses is a library for manipulating the console and the cursor.
OpenGL is a 3D graphics library.
Parrot is also available, through a related but separate development effort as a module for the Apache web server, Mod_Parrot. Mod_Parrot allows Parrot and the high-level languages which target it to be used in Apache to generate web content. Several libraries are available in the Parrot repository that can help manage these requests.