Awesome Functional Python
A curated list of awesome things related to functional programming in Python.
Official documentation
- Functional Programming HOWTO - "In this document, we’ll take a tour of Python’s features suitable for implementing programs in a functional style".
Books
Free books / ebooks
- Functional Programming in Python - Book by David Mertz (O'Reilly).
Non-free books
- Functional Python Programming - Book by Steve Lott (Packtpub, 2015).
Talks
Introductory
- Functional Programming with Python (slides) - Alexey Kachayev, UA PYCon 2012.
- Purely Functional Programming in Python: Pure Fun (slides) - Christopher Armstrong, PyTenessee 2015.
- Side Effects are a Public API (video) - Christopher Armstrong, Strangeloop 2015
- Functional Programming with Python (video) - Mike Müller, PyCon US 2013.
- Using Functional Programming for efficient Data Processing and Analysis (video) - Reuben Cummings, PyCon US 2017.
- Immutable Programming Writing Functional Python (slides, video), Calen Pennington, PyCon 2017.
- Functional Programming inside OOP? It’s possible with Python (Slides) - Carlos Villavicencio, EuroPython 2021.
- A Hitchhiker’s Guide to functools (Slides) - Scott Irwin, EuroPython 2021.
Advanced or specialized
- Functionalish programming in Python with effect (video), Robert Collins, NZ PyCon 2015.
- Monadic Parsing in Python (slides), Alexey Kachayev, KyivPy 2014.
- Immutability and Python - Introducing Pyrsistent (slides), Tobias Gustafsson, 2014.
- Understanding Transducers (slides, video), Austin Bingham, PyCon Belarus 2015.
Data science oriented
- Functional Performance with Core Data Structures (video), Matthew Rocklin, PyData SV 2014.
- Old School - Functional Data Analysis (video), Matthew Rocklin, PyData NYC 2013.
- Learning Data Science Using Functional Python (video, slides), Joel Grus, PyData Seattle 2015.
Other resources
Video lectures (not free)
- Functional Programming with Python - by Christopher Armstrong, O'Reilly.
- Functional Programming in 7 days - by Mohammed Kashif, Udemy.
- Functional Programming in Python - by Dan Bader, Real Python.
Blog posts
- Origins of Python's "Functional" Features, Guido Van Rossum, 2009.
- A practical introduction to functional programming (with examples in Python), by Mary Rose Cook (year unknown).
- Immutable data structures in Python, Robert Rees, 2014.
- Understanding Transducers through Python, by Robert Smallshire. "In this 8 parts series we take an in-depth look at transducers. Transducers – a portmanteau of ‘transform reducers’ – are a new functional programming concept introduced into the Clojure programming language."
- Thinking Functionally with Python and Django at eShares Inc., Kyle Hanson, 2017.
- Simple dependent types in Python - Nikita Sobolev, 2019.
- Python exceptions considered an anti-pattern, Nikita Sobolev, 2019.
- Enforcing Single Responsibility Principle in Python - Nikita Sobolev, 2019.
- Typed functional Dependency Injection in Python - Nikita Sobolev, 2020.
- 4 Part Series on Functional Programming Techniques and Design In Python M. Kocher, 2019.
- Typeclasses in Python - N. Sobolev, 2021
- Functools — The Power of Higher-Order Functions in Python - M. Heinz, 2021
Scientific papers
- Practical Functional Reactive Programming (PDF), John Peterson, Ken Roe, and Alan Cleary, 2014.
Presentation slides
- Python Generators, Samuel Lampa, From talk at PySthlm meetup, Oct 2013
Libraries
General
-
toolz ★3752 - "A functional standard library for Python".
-
fn.py ★3163 - "Functional programming in Python: implementation of missing features to enjoy FP" (unmaintained since 2014).
-
funcy ★2689 - "A fancy and practical functional tools".
-
more-itertools ★2244 - "More routines for operating on iterables, beyond itertools".
-
PyFunctional ★1941 - "Python library for functional programming with collections in a data pipeline style".
-
hask ★838 - "Haskell language features and standard libraries in pure Python".
-
Pydash ★886 - "The kitchen sink of Python utility libraries for doing "stuff" in a functional way. Based on the Lo-Dash Javascript library".
-
Expression ★159 - "Pragmatic functional programming for Python inspired by F#". Successor of OSlash.
-
OSlash ★626 - "Functors, Applicatives, And Monads in Python".
-
Effect ★333 - "Effect isolation in Python, to facilitate more purely functional code".
-
result ★384 - A simple Rust like Result type for Python 3. Fully type annotated.
-
Underscore.py ★277 - "A Python port of excellent javascript library underscore.js".
-
pyramda ★123 - "Python package supporting heavy functional programming through currying. Translation of the Ramda library from javascript to python".
-
Phi ★121 - "A library that intends to remove as much of the pain as possible from your functional programming experience in Python."
-
fnc ★139 - "Functional programming in Python with generators and other utilities".
-
pfun ★114 - "Pure functional programming in python".
-
PyMonad - "a small library implementing monads and related data abstractions -- functors, applicative functors, and monoids -- for use in implementing functional style programs".
-
pyMonet ★28 - "High abstract python library for functional programming. Contains algebraic data structures known from Haskell or Scala".
-
unpythonic ★46 - "Supercharge your Python with parts of Lisp and Haskell."
-
ziopy ★41 - "ZIO for Python (with ZIO = A type-safe, composable library for async and concurrent programming in Scala)"
Return types
- returns ★2015 - "Make your functions return something meaningful, typed, and safe!"
- Option ★15 - Rust-like Option and Result types in Python.
- Meiga ★18 - A simple, typed and monad-based Result type for Python.
- Safetywrap ★22 - Fully typesafe, Rust-like Result and Option types for Python.
Immutable / persistent data structures
- Pyrsistent ★1618 - "Persistent/Immutable/Functional data structures for Python".
- Immutables ★898 - "An immutable mapping type for Python."
- Discodb ★95 - "An efficient, immutable, persistent mapping object".
- Funktown ★74 - "Immutable Data Structures for Python".
- Amino ★31 - "functional data structures and type classes".
- Pysistence - "Pysistence is a project that seeks to make functional programming in python easier".
Pattern matching
(Pattern matching is now a standard feature in Python 3.10).
- pampy ★3419 - "Pampy: The Pattern Matching for Python you always dreamed of."
- python-pattern-matching ★156 - "Python pattern matching like functional languages."
- patmat ★32 - "Functional-style recursive pattern matching in Python. Crazy stuff."
- apm ★89 - "Pattern Matching for Python 3.8+ in a simple, yet powerful, extensible manner."
Tranducers
- Tranducers-Python ★190 - "Transducers are composable algorithmic transformations".
- Transducers ★51 - "This is a port of the transducer concept from Clojure to Python, with an emphasis on providing as Pythonic as interpretation of transducers as possible, rather than reproducing Clojurisms more literally".
Support for reactive style
- RxPy ★4081 - "Reactive Extensions for Python".
- broqer ★64 - "Library to operate with continuous streams of data in a reactive style"
Lenses and declarative data manipulations
- Glom ★1438 - "Python's nested data operator (and CLI), for all your declarative restructuring needs.".
- python-lenses ★208 - "A python lens library for manipulating deeply nested immutable structures".
Other / specialized
- deal ★268 - "Design by contract for Python with many validators support."
- chainable ★167 - "Method chaining built on generators".
- ADT ★137 - Algebraic data types for Python
- sumtypes ★36 - "Sum Types, aka Tagged Unions, for Python".
- python-mini-lambda ★10 - "Simple Lambda functions without lambda x: and with string conversion capability"
Languages
Functional programming languages that are not Python but are related to the Python ecosystem:
- Hy - "A dialect of Lisp that's embedded in Python".
- Coconut - "Simple, elegant, Pythonic functional programming".
- Mochi ★906 - "A dynamically typed programming language for functional programming and actor-style programming.".
- Tydy ★49 - "Tydy is a statically typed, functional-first programming language in the ML tradition. tydy is an implementation of Tydy as a Python library."
- dg (aka dogelang) - "A programming language that compiles to CPython bytecode, much like Scala compiles to JVM's. That essentially means that dg is an alternative syntax for Python 3."
- pixie ★2305 - "A lightweight and native lisp built in RPython". (Discussion on HN)
- Pycket ★219 - "A rudimentary Racket implementation using RPython".
- (How to Write a (Lisp) Interpreter (in Python)) and (An ((Even Better) Lisp) Interpreter (in Python)) - a couple of famous articles by Peter Norvig.