What are the best languages for learning functional programming?

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27 Options Considered

Best languages for learning functional programming	Price	Current stable version	Site
89 Elm	-	0.19	http://elm-lang.org/
89 Haskell	-	-	https://www.haskell.org/
86 F#	-	4.1	-
85 Clojure	-	1.10.1	www.clojure.org
82 Elixir	-	1.11.2	https://elixir-lang.org

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score 64 · Answer 1

Elm

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score 138 · Answer 2

Haskell

F#

Top Pro

Concise syntax

F#'s syntax tends to be terse while remaining very readable and easy to understand without being a chore to write. See More

Top Con

Has no ad-hoc polymorphism (á la Type Classes)

You have generics, you have interfaces, you have inheritance, you have a lot of things at your disposal but you don't have Type Clases. They can be emulated using some clever constructs but there's nothing like having the real thing. See More

Ernesto Barros's Experience

It looks so much like Elm and it works everywhere. With great community and very friendly Editor! If you like Elm then you ought to look at F# :-) They are so good at explaining new ideas. You will always be on the frontline of adopting new technologies!! Which is a big + to me!! See More

Specs

Current stable version:4.1

License:Apache 2.0

Clojure

Top Pro

Immutability is the default

Clojure programmers are highly encouraged to use immutable data in their code. Therefore, most data will be immutable by default. State change is handled by functions (for transformations) and atoms (an abstraction that encapsulates the idea of some entity having an identity). See More

Top Con

Confusing error messages

Clojure's error messages more often than not are very confusing. They usually involve stack traces that do not thoroughly explain where the error was caused or what caused it. See More

LovelyPoseidon's Experience

It's a LISP See More

Specs

Current stable version:1.10.1

Site:www.clojure.org

Price:Free, Open Source

Platforms:Windows, Linux, Mac

Elixir

Top Pro

Great for concurrency

Leverages the existing Erlang BEAM VM See More

Top Con

Deployment is still not as easy as it should be

Hilko's Experience

I've been a fan of functional programming for a long time, but either found the language I used a bit too daunting (Haskell, Clojure had me wrap my head around FP ánd Lisp), or too forgiving (JS offers too many anti-functional escape hatches, for example). Elixir was exactly the right amount of enforced FP combined with familiar and elegant syntax, and the advantages unique to a language on the BEAM VM were initially just gravy, and now a reason for me to stay within the ecosystem. See More

Specs

Current stable version:1.11.2

Site:https://elixir-lang.org

Price:Open source (Free)

Scheme

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15

Since the syntax is easy and it's clear how everything works, it's easy to see how the program is running. See More

Top Pro

Definition of functional language

Part of the family of languages that started the concept. Pure functional programming is a subset of functional programming and should not be confused with functional programming proper. See More

See All

score 17 · Answer 7

Idris

OCaml

Racket

Top Pro

Realm of Racket is an excellent entry-level guidebook

Realm of Racket teaches the big-bang approach for managing world state. It does so by walking the reader through the development of small games. There are few guidebooks that are as useful and entertaining. See More

ArtisticSalacia's Experience

I used racket-lang to learn the most important aspects of functional programming. It comes with a real wealth of useful libraries for graphics, databases, mathematics, text processing etc. There is also a type system called typed racket which reflects modern views to functional programming. See More

Specs

Current stable version:7.8

Site:https://racket-lang.org

Price:Free

Platforms:Linux, Windows, OSX

Scala

Top Pro

Compiles to JVM bytecode, making applications written in Scala cross-platform

Aside from Java itself, Scala is by far the most popular of the many JVM languages. If you're developing for Android, or a similar JVM-only platform, or otherwise need out-of-the-box cross-platform compatibility, but the performance of a compiled language, Scala is the way to go. See More

Top Con

Can be intimidating for beginners

Scala is an industrial language. It brings functional programming to the JVM, but not with a "start small and grow the language" perspective, but rather a very powerful language for professional programmers. See More

Specs

Current stable version:2.13.1

Site:scala-lang.org

Go

Top Pro

Simplified C-like syntax that is as easy to read and write as Python

The language is designed in a manner that seems logical. Syntax is simplified to reduce burden on the programmer and compiler developers. See More

Top Con

Hard to abstract even the simplest notions

Go is famously regarded as very simple. However, this simplicity becomes problematic in time. Programmers who use Go find themselves over and over again writing the same thing from a very low point of view. Domains not already served by libraries that are easy to glue are very difficult to get into. See More

Specs

Current stable version:1.15 / August 11, 2020

Platforms:Windows, Linux, Mac etc.

GZipped size:115 MB (installer)

PureScript

Ceylon

Top Pro

Excellent type system

Intersection and union types make expressing some concepts very easy and intuitive See More

Top Con

Although it supports functional programming, it's above all an object oriented language

Specs

Current stable version:1.3.2

Site:http://ceylon-lang.org

Price:Free, Open Source

Top Pro

Regular syntax

Makes it very easy to parse and read code See More

Top Pro

Local type inference

Removes a lot of boilerplate See More

Top Pro

Great support for processing lazy streams

Ceylon has great support for processing lazy streams using higher order functions and comprehensions. See More

See All

score 15 · Answer 14

Kotlin

Top Pro

Great tooling support

Since Kotlin is made by Jetbrains (the developers of IntelliJ IDEA) so it stands to reason that the IntelliJ support for Kotlin is also great. Besides that, Kotlin also works well with existing Java tools such as Eclipse, Maven, Gradle, Android Studio, etc... See More

Top Con

May be hard for programmers already used to imperative style to learn functional programming from Kotlin

Since Kotlin does not enforce any particular paradigms and is not purely functional, it can be pretty easy to fall back to imperative programming habits if a programmer comes from an imperative background. See More

Specs

Current stable version:1.3

Site:http://kotlinlang.org

Kotlin has been designed and built by developers who have an industrial background and not an academic one. As such, it tries to solve issues mostly found in industrial settings. For example, the Kotlin type system helps developers avoid null pointer exceptions. Reasearch languages usually do not have null at all, but APIs and large codebases usually need null. See More

See All

score 8 · Answer 15

Standard ML

Erlang

Top Pro

Battle proven

Erlang has been used in production for more than 20 years now. During that time it has proven itself over and over again that works great in both small startups and large-scale enterprise systems. Erlang has been used extensively by Ericsson themselves. For example, the AXD301 ATM, which is one of Ericsson's flagships is probably the largest Erlang project ever with more than 1.1 million lines of Erlang code. See More

Top Con

Strange syntax

Erlang's syntax may feel very strange to 99% of programmers who have never used it. This is because it does not share any similarities or common syntax definitions that are found in all the other languages that are used today. See More

Deuxis's Experience

Erlang's eccentric syntax and features were created to be natural for humans, not just for programmers used to the C style. Functions (or rather, all blocks/statements) are structured like sentences, with commas separating the instructions, semicolons separating overloads of the same function and a period marking the end. Dynamic but strong typing means that types are no concern but there are no weird implicit conversions. Destructuring operations are the standard. The ultra-light and easy to manage processes communicating via messages are basically the dream of anyone wanting to touch concurrency. There is even an entire section of the language dedicated to parsing and constructing binary blobs in an intuitive way. See More

See All

score 3 · Answer 17

Reason ML

Top Pro

Being able to access both JavaScript (NPM) and OCaml (Dune) ecosystems and packages

FerventSors's Experience

I came from a JavaScript/Java/Python (C-like) background and ReasonML really ease the scare of learning FP by being much syntactically C-like and having a very modern culture and tool chains. See More

Specs

Price:Free, Open source

Version:3.6.0

Top Pro

Easy development environment (e.g. Compiler, Editor tooling) setup

Top Pro

Uses established compiler technology from Ocaml with a tweaked syntax that leans more towards Javascript

See All

score 5 · Answer 18

Rust

Top Pro

Great Documentation

Rust has an official documentation and tutorial and tools for generating docs for libraries See More

ImpartialNannaNepsdottir's Experience

Best See More

Specs

Current stable version:1.4.0

Platforms:Linux, MacOS X, Windows, BSD

Since Rust 1.8 you can install additional versions of the standard library for different targets using rustup/multirust. For example: $ rustup target add x86_64-unknown-linux-musl Which then allows for: $ cargo build --target x86_64-unknown-linux-musl See More

See All

score 5 · Answer 19

JavaScript

Top Pro

Required for web development

If you are looking to create web projects, you will have to learn Javascript in order to develop the client side code. If you learn the foundations of programming in JavaScript you can reapply that education later in building web applications. See More

Specs

Engine:V8/ChakraCore

Author:Ryan Dahl/Joyent

Version(Latest):12.x

ECMAScript Modules:Available (as a flag) (only on Node 8.x-10.x)

Nim

Top Pro

Garbage-collected

You don't need to deal with all those manual memory allocations, Nim can take care of it. But also you can use another GC, or tweak it for your real-time application or a game. See More

Top Con

Still in pre 1.0

The same code can be used for web, server, desktop and mobile. See More

ArtisticAmaethon's Experience

Produces fast code on a par with C and much faster than scripting languages like Python, Ruby, Perl etc See More

Specs

Current stable version:1.4.4

Site:https://nim-lang.org

Platforms:Windows, MacOS/iOS, Linux /Android/Termux, *BSD, Solaris/SmartOS, HaikuOS, lots of others

GZipped size:13 MB

Nim has a built-in VM, which executes macros and some other code at compile time. For example, you can check if you're on Windows, and Nim will generate code only for it. See More

Top Pro

Built-in Unicode support

You can use unicode names for variables, there is "unicode" module for operations with unicode. See More

27 Options Considered

My Recommendation for Elm

My Recommendation for Elm

Compile errors are human-friendly

Missing syntactic sugar ('where' clauses, pattern guards)

The Elm architecture offers a simple pattern for all programs

No Genericness in the future

Avoids advanced FP topics such as Monads

Code Repetition

Easier to make front ends than JS

Issues are swept under the rug

Growing community

Updates break existing code often

No run-time exceptions

Good for beginners, not good for experts

Good tooling

Community harsh if criticised

Good documentation

Features get removed without warning

Inferred static typing

Limited js interop

Super easy refactoring with very helpful compiler errors

Lack of typeclasses

Static module system

Not quite Haskell semantics

Great and simple way to learn Purely Functional Programming

No higher-kinded types

Designed around high-level front-end development

Missing syntactic sugar

Simpler syntax than Haskell

Instant gratification with GUI's

Batteries included

Reactive programming is baked in

Higher confidence in code correctness and quality

Easy to code review

Time-travelling debugger and Hot-swapping of code

Tailor-made for games

High-level Functional-Reactive Code

My Recommendation for Haskell

My Recommendation for Haskell

Forces you to learn pure functional programming

Language extensions lead to unfamiliar code

Open source

Difficult learning curve

Highly transferable concepts

Package manager is unstable & lacking features

Mathematical consistency

You have to learn more than just FP

Referentially transparent

Symbols everywhere

Hand-writeable concise syntax

Obscure ugly notation

Very few language constructs

Documentation for most packages is short and lacking

Quick feedback

Too academic, hard to find "real world" code examples

Functions curry automatically

You need some time to start seeing results

Easy to read

Lazily evaluated

Popular in teaching

Only pure functional programming

Easy syntax for people with a STEM degree

Curried type signatures obfuscate what were the in and out types originally

Powerful categorical abstractions

My Recommendation for F#

My Recommendation for F#

Concise syntax

Has no ad-hoc polymorphism (á la Type Classes)

Easier transition from other paradigms

.NET Interoperability

Multiplatform, it runs on .Net Core

You can run F# in the browser

Natively supported by Visual Studio

Allows writing predictable code

Fall into the pit of success

Type Providers

F# is supported by Xamarin

My Recommendation for Clojure

My Recommendation for Clojure