Editing Perl Data Language (section)

==Implementation==
The core of PDL is written in [[C (programming language)|C]]. Most of the functionality is written in '''PP''', a PDL-specific metalanguage that handles the vectorization of simple C snippets and interfaces them with the Perl host language via Perl's [[XS (Perl)|XS]] compiler. Some modules are written in [[Fortran]], with a C/PP interface layer. Many of the supplied functions are written in PDL itself. PP is available to the user to write C-language extensions to PDL. There is also an Inline module (Inline::Pdlpp) that allows PP function definitions to be inserted directly into a Perl script; the relevant code is low-level compiled and made available as a Perl subroutine.

The PDL API uses the basic Perl 5 object-oriented functionality: PDL defines a new type of Perl scalar object ([[eponym]]ously called a "PDL", or "ndarray") that acts as a Perl scalar, but that contains a conventional [[data type|typed]] [[Array data type|array]] of numeric or character values. All of the standard Perl operators are overloaded so that they can be used on PDL objects transparently, and PDLs can be mixed-and-matched with normal Perl scalars. Several hundred object methods for operating on PDLs are supplied by the core modules.