Python

Python is a general-purpose high-level programming language. Its design philosophy emphasizes code readability. Python claims to "remarkable power with very clear syntax", and its standard library is large and comprehensive. Its use of indentation as block delimiters is unusual among popular programming languages.

Python supports multiple programming paradigms (primarily object oriented, imperative, and functional) and features a fully dynamic type system and automatic memory management, similar to Perl, Ruby, Scheme, and Tcl. Like other dynamic languages, Python is often used as a scripting language.

The language has an open, community-based development model managed by the non-profit Python Software Foundation, which maintains the de facto standard definition of the language in CPython, the reference implementation.

Programming philosophy

Python is a multi-paradigm programming language. Rather than forcing programmers to adopt a particular style of programming, it permits several styles: object-oriented programming and structured programming are fully supported, and there are a number of language features which support functional programming and aspect-oriented programming (including by metaprogramming and by magic methods). Many other paradigms are supported using extensions, such as pyDBC and Contracts for Python which allow Design by Contract.

Python uses dynamic typing and a combination of reference counting and a cycle-detecting garbage collector for memory management. An important feature of Python is dynamic name resolution (late binding), which binds method and variable names during program execution.

Rather than requiring all desired functionality to be built into the language's core, Python was designed to be highly extensible. New built-in modules can be easily written in C or C++. Python can also be used as an extension language for existing modules and applications that need a programmable interface. This design of a small core language with a large standard library and an easily extensible interpreter was intended by Van Rossum from the very start because of his frustrations with ABC (which espoused the opposite mindset).

The design of Python offers only limited support for functional programming in the Lisp tradition. However, Python's design philosophy exhibits significant similarities to those of minimalist Lisp-family languages, such as Scheme. The library has two modules (itertools and functools) that implement proven functional tools borrowed from Haskell and Standard ML.

While offering choice in coding methodology, the Python philosophy rejects exuberant syntax, such as in Perl, in favor of a sparser, less-cluttered grammar. Python's developers expressly promote a particular "culture" or ideology based on what they want the language to be, favoring language forms they see as "beautiful", "explicit" and "simple". As Alex Martelli put it in his Python Cookbook (2nd ed., p.230): "To describe something as clever is NOT considered a compliment in the Python culture." Python's philosophy rejects the Perl "there is more than one way to do it" approach to language design in favor of "there should be one—and preferably only one—obvious way to do it".

Python's developers eschew premature optimization, and moreover, reject patches to non-critical parts of CPython which would offer a marginal increase in speed at the cost of clarity. It is sometimes described as "slow". However, by the Pareto principle, most problems and sections of programs are not speed critical, and as computer hardware continues to become exponentially faster (Moore's Law), languages do have more hardware resources available. When speed is a problem, Python programmers tend to try to optimize bottlenecks by algorithm improvements or data structure changes, using a JIT compiler such as Psyco, rewriting the time-critical functions in "closer to the metal" languages such as C, or by translating Python code to C code using tools like Cython.