Shed Skin is an experimental restricted- Python (3.8+) to C++ programming language

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

. It can translate pure, but implicitly statically typed Python programs into optimized C++. It can generate stand-alone programs or extension modules that can be imported and used in larger Python programs. Shed Skin is an open source project with contributions from many people, however the main author is Mark Dufour. Work has been going into Shed Skin since 2005.first Shed Skin release
/ref>

Features

Besides the typing restriction, programs cannot freely use the Python standard library, although about 20 common modules, such as random, itertools and re (

regular expression A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" ...

s), are supported as of 2011. Also, not all Python features, such as

nested function In computer programming, a nested function (or nested procedure or subroutine) is a named function that is defined within another, enclosing, block and is lexically scoped within the enclosing block meaning it is only callable by name within t ...

s and variable numbers of arguments, are supported. Many introspective dynamic parts of the language are unsupported. For example, functions like getattr, and hasattr are unsupported. As of May 2011,

Unicode Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...

is not supported. As of June 2016 for a set of 75 non-trivial test programs (at over 25,000 lines of code in total), measurements show a typical speedup of 2-20 times over Psyco, and 2-200 times over

CPython CPython is the reference implementation of the Python programming language. Written in C and Python, CPython is the default and most widely used implementation of the Python language. CPython can be defined as both an interpreter and a comp ...

.Speed up your Python: Unladen vs. Shed Skin vs. PyPy vs. Cython vs. C
/ref>Taking on Shed-Skin
/ref>Speeding up Python code with Shed Skin
/ref>MiniLight, minimal global illumination renderer benchmark
/ref> Shed Skin is still in an early stage of development, so many other programs will not compile unmodified.Shed Skin webpage
/ref> Shed Skin can be used to generate standalone executables which need only the C++ runtime libraries. It can also be used to generate CPython modules. This allows compiling parts of larger programs with Shed Skin, while running the other parts using regular CPython. Another use has been to wrap C++ classes using Shed Skin to allow C++ classes to be used as Python classes.Wrapping C++ classes using Shed Skin
/ref> The license of the Shed Skin source code is under two parts. The main compiler code is under the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

(GPL). The supporting code that it uses as a run time library is under a

BSD The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginni ...

or MIT license depending on the module. This allows compiling both GPL and non-GPL programs.

Type inference

Shed Skin combines Ole Agesen's Cartesian Product Algorithm (CPA) with the data-polymorphic part of John Plevyak's Iterative Flow Analysis (IFA).Master Thesis Mark Dufour, "Shed Skin. An Optimizing Python-to-C++ Compiler"
April 19, 2006 Version 0.6 introduced scalability improvements which repeatedly analyze larger versions of a program (in addition to the mentioned techniques), until it is fully analyzed. This allows Shed Skin to do

type inference Type inference, sometimes called type reconstruction, refers to the automatic detection of the type of an expression in a formal language. These include programming languages and mathematical type systems, but also natural languages in some bran ...

on larger programs than previously. It starts with an empty callgraph, essentially, and slowly adds to it, until the whole call graph has been added. A graph has been published by the author, showing analysis times for 50 example programs, at a total of around 15,000 lines.Type inference scalability
2010-12

Modules

For version 0.9 the following 25 modules are largely supported.