PyPy

PyPy is an implementation of the <a href="/facts/Python_(programming_language)/YbuGqofa">Python</a> <a href="/facts/Programming_language/cWTYbgWa">programming language</a>. PyPy often runs faster than the standard <a href="/facts/Implementation/IH1KXgP3">implementation</a> <a href="/facts/CPython/kMhXKEGC">CPython</a> because PyPy uses a <a href="/facts/Just-in-time_compilation/rEYDsd8l">just-in-time compiler</a>. Most Python code runs well on PyPy except for code that depends on CPython extensions, which either does not work or incurs some overhead when run in PyPy.
PyPy itself is built using a technique known as meta-tracing, which is a mostly automatic transformation that takes an <a href="/facts/Interpreter_(computing)/JB85fbyb">interpreter</a> as input and produces a <a href="/facts/Tracing_just-in-time_compilation/4z30Rkoc">tracing just-in-time compiler</a> as output. Since interpreters are usually easier to write than <a href="/facts/Compiler/WNfCDFJe">compilers</a>, but run slower, this technique can make it easier to produce efficient implementations of programming languages. PyPy's meta-tracing <a href="/facts/Toolchain/SmlWCJhY">toolchain</a> is called RPython.
PyPy officially supports Python 2.7 and 3.10 and has a few differences in implementations compared to CPython.

PyPy open-in-new

PyPy