Awesome Functional Python

A curated list of awesome things related to functional programming in Python.

• Official documentation
• Books
• Talks
• Other resources
• Libraries
• Languages

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 by David Mertz (O'Reilly)

Non-free books

• Functional Python Programming, 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

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

• Functional Programming with Python, by Christopher Armstrong, O'Reilly.
• Functional Programming in 7 days, by Mohammed Kashif, Udemy.

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.
• Python exceptions considered an anti-pattern, Nikita Sobolev, 2019.
• Simple dependent types in Python - Nikita Sobolev, 2019.

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

• fn.py ★2600 - "Functional programming in Python: implementation of missing features to enjoy FP" (unmaintained since 2014).
• toolz ★1700 - "A functional standard library for Python".
• funcy ★1700 - "A fancy and practical functional tools".
• PyFunctional ★1200 - "Python library for functional programming with collections in a data pipeline style".
• hask ★580 - "Haskell language features and standard libraries in pure Python".
• more-itertools ★460 - "More routines for operating on iterables, beyond itertools".
• Underscore.py ★250 - "A Python port of excellent javascript library underscore.js".
• Effect ★240 - "Effect isolation in Python, to facilitate more purely functional code".
• OSlash ★230 - "Functors, Applicatives, And Monads in Python".
• returns ★165 - "Make your functions return something meaningful, typed, and safe!"
• Pydash ★160 - "The kitchen sink of Python utility libraries for doing "stuff" in a functional way. Based on the Lo-Dash Javascript library".
• pyramda ★50 - "Python package supporting heavy functional programming through currying. Translation of the Ramda library from javascript to python".
• PyMonad - "a small library implementing monads and related data abstractions -- functors, applicative functors, and monoids -- for use in implementing functional style programs".
• Amino - "functional data structures and type classes".
• deal - "Design by contract for Python with many validators support."
• pyMonet - "High abstract python library for functional programming. Contains algebraic data structures known from Haskell or Scala".
• f - "Pure functional programming in python".
• fnc - "Functional programming in Python with generators and other utilities".
• Phi - "A library that intends to remove as much of the pain as possible from your functional programming experience in Python."

Immutable / persistent data structures

• Pyrsistent ★500 - "Persistent/Immutable/Functional data structures for Python".
• Funktown ★60 - "Immutable Data Structures for Python".
• Discodb ★50 - "An efficient, immutable, persistent mapping object".
• Pysistence - "Pysistence is a project that seeks to make functional programming in python easier".
• Immutables - "An immutable mapping type for Python."

Other / specialized

• Transducers - "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".
• Tranducers-Python - "Transducers are composable algorithmic transformations".
• RxPy - "Reactive Extensions for Python".
• python-lenses - "A python lens library for manipulating deeply nested immutable structures".
• sumtypes - "Sum Types, aka Tagged Unions, for Python".
• chainable - "Method chaining built on generators".
• broqer - "Library to operate with continuous streams of data in a reactive style"
• python-mini-lambda - "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 - "A dynamically typed programming language for functional programming and actor-style programming.".
• Tydy - "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 - "A lightweight and native lisp built in RPython". (Discussion on HN)
• Pycket - "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.

(More languages that compile to Python)