Top 13 C++ Functional programming Projects

nix

193 7,790 9.9 C++

Nix, the purely functional package manager

Project mention: Why is the "minimal" official docker nix image over 700M?(`/nix/store` won't free old packages?) | reddit.com/r/NixOS | 2023-03-31

Is https://github.com/NixOS/nix/blob/master/docker.nix where it is built from? At least the package list matches https://nixos.org/manual/nix/stable/installation/installing-docker.html
faust

23 2,116 9.8 C++

Functional programming language for signal processing and sound synthesis (by grame-cncm)

Project mention: Ask HN: What audio/sound-related OSS projects can I contribute to? | news.ycombinator.com | 2023-03-22

I heard of https://github.com/grame-cncm/faust a while back, probably via HN. It looks interesting and actively maintained, but I didn’t get a chance to play with it. There are many other libraries listed on GitHub awesome lists such as this one: https://github.com/ad-si/awesome-music-production#libraries
InfluxDB

www.influxdata.com
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FunctionalPlus

2 1,782 4.3 C++

Functional Programming Library for C++. Write concise and readable C++ code.

Project mention: C++ algorithm helpers - kdalgorithms | reddit.com/r/cpp | 2022-12-10

You can get a feel for it on its api search site: as an example, enter these queries:
jank

11 1,009 9.7 C++

A Clojure dialect on LLVM with gradual typing, a native runtime, and C++ interop

Project mention: Janet for Mortals | news.ycombinator.com | 2023-03-31

I wonder if Jank [1] could be such a Lisp? I haven't played around with it, but I really like the idea and would love to see it get more traction.
[1]: https://jank-lang.org/
lager

3 603 6.0 C++

C++ library for value-oriented design using the unidirectional data-flow architecture — Redux for C++

Project mention: HikoGUI v0.7.0, A fast desktop application GUI library in C++20. (BSL license) | reddit.com/r/cpp | 2022-10-17

observer: I changed how observer<> works, this is basically a template-class which observes a value and then calls a registered callback on modification. It can now create a sub-observer<> from a member variable of the value it observers. This makes it possible for widgets to be composable. This is based loosely on lager's lenses and cursors.
hof

1 488 10.0 C++

Higher-order functions for c++ (by boostorg)

Project mention: Function composition in modern C++ | reddit.com/r/cpp | 2023-03-05

a prime example of how modern c++ simplified things: “Compose” in hof spans hundreds of lines of code (and needs inclusion of library headers and utilities) https://github.com/boostorg/hof/blob/develop/include/boost/hof/compose.hpp . Just a reminder of what we had to go through very recently to do something that’s now doable in ~15 lines of vanilla C++ . Mad respect for Paul Fultz.
rangeless

0 184 0.0 C++

c++ LINQ -like library of higher-order functions for data manipulation
Sonar

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lift

0 178 0.0 C++

constexpr C++17 library for simplifying higher order functions in application code (by rollbear)
hspp

9 141 8.9 C++

hspp: An experimental library to bring Haskell Style Programming to C++.

Project mention: Chromium accepting Rust in a clear move to copy what Mozilla have done, replace C++ source code | reddit.com/r/cpp | 2023-01-12

Yeah, C++ supports higher kinded types through template templates (I'm not sure why the other poster said it doesn't), however it quickly becomes messy and impractical. Here's a cursed library that attempts to support Haskell-style programming in C++. Here's an example where they implement a monad transformer using the only example of a template template template that I have ever seen in the wild.
egel

0 70 3.3 C++

The Egel Programming Language
recursive-variant

0 66 0.0 C++

Recursive Variant: A simple library for Recursive Variant Types
wyvern

1 44 7.7 C++

Automatic conversion of call by value into call by need in the LLVM IR. (by lac-dcc)

Project mention: Lazification of Function Arguments | reddit.com/r/Compilers | 2022-07-01

For those interested, the code is here: https://github.com/lac-dcc/wyvern
libletlib

0 9 0.0 C++

C++ framework for the impatient.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020). The latest post mention was on 2023-03-31.