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What are the best languages for learning functional programming?

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The Best 2 of 21 OptionsWhy?

21 Options ConsideredPriceSiteCurrent stable version
91
Elm
-http://elm-lang.org/0.18
90
Haskell
-https://www.haskell.org/–
85
Clojure
-www.clojure.org1.9
85
Elixir
-https://elixir-lang.org1.6
82
Scheme
-––
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91
Excellent

Elm

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Dénes Harmath
Gage Peterson
Top Pro

Compile errors are human-friendly

•••
A lot of thought has gone into making the user experience of encountering compile errors as delightful as possible. See more info at http://elm-lang.org/blog/compiler-errors-for-humans.
Mario T. Lanza
Top Pro

The Elm architecture offers a simple pattern for all programs

•••
What could be nicer when creating a program than being able to follow a simple, reusable recipe: model (represent your domain), action (progress your story), view (show it).
Gage Peterson
Top Pro

Easier to make front ends than JS

•••
This is perhaps subjective but I think it holds pretty true.
Gage Peterson
Top Pro

Avoids advanced FP topics such as Monads

•••
This is a great boon to people that want to learn FP but aren't ready for a deep dive into category theory and a bunch of other things.
Endi Sukaj
Top Pro

Growing community

•••
Elm is gaining popularity, somewhat faster than many of the other solutions here. This translates to more code examples, more documentation, and more libraries.
Endi Sukaj
Top Pro

Time-travelling debugger and Hot-swapping of code

•••
Elms purity and high-level FRP primitives allow for similarly higher-level tools that other languages can only dream of.
mailinator
Top Pro

No run-time exceptions

•••
Lack of run-time exceptions makes it easy to produce large swathes of reliable front-end code without drowning in tests.
Mario T. Lanza
Top Pro

Reactive programming is baked in

•••
Functional reactive programming has emerged as a good, straightforward means of modelling change over time. It is well suited to graphical environments. Elm was conceived with FRP in mind.
timlyo
Top Pro

Inferred static typing

•••
ML static typing is great because it's always there, you just choose how explicit you want to be and how much you want the compiler to do.
timlyo
Top Pro

Static module system

•••
Elm uses easy to use modules. Use: import Listimport List as Limport List exposing (..)import List exposing ( map, foldl )import Maybe exposing ( Maybe )import Maybe exposing ( Maybe(..) )import Maybe exposing ( Maybe(Just) ) Creation: module MyModule exposing (foo, bar)
Mario T. Lanza
Top Pro

Tailor-made for games

•••
While it might not have been created as a game engine, it was created as a platform for rendering graphical UIs. Couple this with the simple Elm Architecture and you have a standalone platform that is ready for indie-game development.
timlyo
Top Pro

Good tooling

•••
All major editors have great support. With Atom for example, Elm plugins are available for linting, formatting, make/compiler support and Elmjutsu will simply overflow you with super useful functions, like navigate to referenced definition and show expression type.
timlyo
Top Pro

High-level Functional-Reactive Code

•••
Build animations, games, and interactions with an incredibly small amount of terse, readable code.
timlyo
Top Pro

Good documentation 

•••
Elm is gaining popularity, somewhat faster than many of the other solutions here. This translates to more code examples, more documentation, and more libraries.
NonchalantPassalos
Top Pro

Designed around high-level front-end development 

•••
As Elm was designed as a front-end langauge, it has out of the box support for things like DOM-element creation, letting programmers focus on their application logic, rather than implementation details specific to the web.
Endi Sukaj
Top Con

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

•••
Elm is missing a lot of syntactic sugar that Haskellers may consider core, such as 'do' notation, 'where' clauses, pattern guards, and operator sections.
SociablePoena
Top Con

Not quite Haskell semantics 

•••
Elm is a strict language, semantically different from Haskell. Elm also borrows a lot from OCaml and F#. While this makes for a nice syntax, it does mean that, for the Haskell programmer, there may be some surprises when it comes to semantics or function names.
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90
Excellent

Haskell

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David
Endi Sukaj
Gage Peterson
Top Pro

Forces you to learn pure functional programming

•••
It is pure and does not mix other programming paradigms into the language. This forces you to learn functional programming in its most pure form. This avoids you falling back on old habits and learn an entirely new way to program.
Endi Sukaj
Peter Zeller
Top Pro

Open source

•••
All Haskell implementations are completely free and open source.
Ray
Andris Pelcbergs
Top Pro

Highly transferable concepts

•••
Haskell's referential transparency, consistency, mathematics-oriented culture, and heavy amount of abstraction encourage problem solving at a very high level. The fact that this is all built upon little other than function application means that not only is the thought process, but even concre...
Andris Pelcbergs
Top Pro

Very few language constructs 

•••
The base language relies primarily on function application, with a very small amount of special-case syntax. Once you know the rules for function application, you know most of the language.
Andris Pelcbergs
Top Pro

Mathematical consistency 

•••
As Haskell lends itself exceedingly well to abstraction, and borrows heavily from the culture of pure mathematics, it means that a lot more code conforms to very high-level abstractions. You can expect code from vastly different libraries to follow the same rules, and to be incredibly self-consiste...
Endi Sukaj
Andris Pelcbergs
Top Pro

Referentially transparent

•••
Haskell's Purely Functional approach means that code is referentially transparent. This means that to read a function, one only needs to know its arguments. Code works the same way that expressions work in Algebra class. There's no need to read the whole source code to determine if there...
Andris Pelcbergs
Top Pro

Quick feedback 

•••
It's often said that, in Haskell, if it compiles, it works. This short feedback loop can speed up learning process, by making it clear exactly when and where mistakes are made.
Jooyung Han
Top Pro

Hand-writeable concise syntax

•••
Conciseness of Haskell lets us to write the expression on the whiteboard or paper and discuss with others easily. This is a strong benefit to learn FP over other languages.
Endi Sukaj
Andris Pelcbergs
Top Pro

Easy to read

•••
Haskell is a very terse language, particularly due to its type inference. This means there's nothing to distract from the intent of the code, making it very readable. This is in sharp contrast to languages like Java, where skimming code requires learning which details can be ignored. Haskell...
Endi Sukaj
Mario T. Lanza
Top Pro

Functions curry automatically

•••
Every function that expects more than one arguments is basically a function that returns a partially applied function. This is well-suited to function composition, elegance, and concision.
Endi Sukaj
Peter Zeller
Top Pro

Popular in teaching

•••
Haskell is really popular in universities and academia as a tool to teach programming. A lot of books for people who don't know programming are written around Haskell. This means that there are a lot of resources for beginners in programming with which to learn Haskell and functional programmi...
Endi Sukaj
Stuart Kearney
Peter Zeller
Top Pro

Easy syntax for people with a STEM degree

•••
Since the basic syntax is very similar to mathematics, Haskell syntax should be easy for people who have taken higher math courses since they would be used to the symbols used in maths.
gilch
Endi Sukaj
Andris Pelcbergs
Top Con

Difficult learning curve

•••
Haskell lends itself well to powerful abstractions - the result is that even basic, commonly used libraries, while easy to use, are implemened using a vocabularly that requires a lot of backround in abstract mathematics to understand. Even a concept as simple as "combine A and B" is ofte...
Andris Pelcbergs
Top Con

Language Extensions lead to unfamiliar code 

•••
Haskell's language extensions, while making the language incredibly flexible for experienced users, makes a lot of code incredibly unfamiliar for beginners. Some pragmas, like NoMonomorphismRestriction, have effects that seem completely transparent in code, leading beginners to wonder why it...
Endi Sukaj
Andris Pelcbergs
Top Con

Symbols everywhere 

•••
Haskell allows users to define their own infix operators, even with their own precedence. The result is that some code is filled with foreign looking operators that are assumed to be special-case syntax. Even for programmers who know they're just functions, operators that change infix preceden...
Endi Sukaj
Steven Sagaert
Marc Telesha
Top Con

Package manager is unstable & lacking features

•••
Cabal (There are other choices but this is the most popular) can not uninstall a package. Also working at a few locations it is difficult to have the same environment for each one be the same.
Endi Sukaj
Andris Pelcbergs
Top Con

You need some time to start seeing results

•••
Haskell's static typing, while helpful when building a project, can be positively frustrating for beginners. Quick feedback for errors means delaying the dopamine hit of code actually running. While in some languages, a beginner's first experience may be their code printing "Hello Worl...
Endi Sukaj
Andris Pelcbergs
Top Con

Lazily Evaluated 

•••
Haskell's lazy evaluation implies a level of indirection - you're not passing a value, you're passing a thunk. This is often difficult to grasp not just for beginners, but for experienced programmers coming from strictly evaluated languages. This also means that, since for many, strict...
Gage Peterson
Top Con

You have to learn more than just FP

•••
Haskell is not only a functional language but also a lazy, and statically typed one. Not only that but it's almost necessary to learn about monads before you can do anything useful.
Endi Sukaj
rystrm
Top Con

Documentation for most packages is short and lacking

•••
A few Haskell packages are well documented but this is the exception, not the rule. Most of the time a list of function signatures is what passes for documentation.
Endi Sukaj
Steven Sagaert
Top Con

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

•••
Endi Sukaj
Steven Sagaert
Top Con

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

•••
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19 Other Options Considered

85

Clojure

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Endi Sukaj
Mario T. Lanza
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).
Mario T. Lanza
Top Pro

Minimal syntax

•••
Being a LISP, programs are simple: they're just functions and data. That it doesn't get bogged down with syntax or the loftier FP concepts like monads makes it one of most approachable functional languages for beginners.
Endi Sukaj
Top Pro

Tries to solve problems as simply as possible

•••
Simplicity is one of the pillars on which Clojure is built. Clojure tries to solve many problems in software development as simply as possible. Instead of building complex interfaces, objects or factories, it uses immutability and simple data structures.
Endi Sukaj
Top Pro

Good for writing concurrent programs

•••
Since Clojure is designed for concurrency, it offers things like Software Transaction Memory, functional programming without side-effects and immutable data structures right out of the box. This means that the development team can focus their energies on developing features instead of concurrency d...
Endi Sukaj
Top Pro

Huge ecosystem of libraries to work with

•••
There's a very large ecosystem of high-quality Clojure libraries which developers can use. One example is Incanter. It's a great data analytics library and a very powerful tool for dealing with matrices, datasets and csv files.
Endi Sukaj
Top Pro

Cross platform

•••
Clojure compiles to JVM bytecode and runs inside the JVM. This means that applications written in Clojure are cross-platform out of the box.
Gage Peterson
Top Pro

Rich Hickey

•••
The creator is so awesome, he's a feature. Just look up his talks and see why.
Laura Kyle
OrganizedRundas
Top Pro

Extensible

•••
Clojure has an elegant macro system which enables language additions, Domain-specific languages (DSLs), to be created much easier than most other languages (with the exception of Racket, perhaps).
OrganizedRundas
Top Pro

Dynamic language

•••
A superb data processing language. While rich type and specification systems are available they are optional.
Endi Sukaj
Top Pro

Great tool used in automating, configuring and managing dependencies available

•••
Leiningen is a very useful tool for Clojure developers. It helps wiht automation, configuration and dependency management. It's basically a must for every Clojure project.
Endi Sukaj
Gage Peterson
Top Pro

Game is available with which you can learn Clojure

•••
Nightmod is a tool used to make "live-moddable" games. It displays the game's code while you are playing and allows you to inject new code using Clojure. This can be a fun and useful experience for people trying to learn Clojure.
Chloe Montanez
TallTumatauenga
Top Pro

No C/Java syntax

•••
Refreshing, BTW!
Endi Sukaj
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.
rystrm
Top Con

Tied to the JVM and it's limitations.

•••
Some language constructs were obviously created as workarounds for JVM limitations. This makes the language much less elegant than it could have been. Also, the JVM has a very cumbersome FFI.
G. P. II
Top Con

Syntax can be alien / jarring for those used to other Lisps

•••
Perhaps some may consider this attribute an advantage, but I do not. Clojure does not attempt to maintain significant compatibility with other Lisps. So, if you already know a Lisp or are used to the way Lisp works in general, you'll probably be confused if you take a look at Clojure. See these...
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85

Elixir

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Endi Sukaj
Gage Peterson
Top Pro

Great documentation

•••
Elixir's documentation is very good. It covers everything and always helps solving any problem you may have. It's also always available from the terminal.
Joe Seeley
Top Pro

Great for concurrency

•••
Leverages the existing Erlang BEAM VM
Gage Peterson
Top Pro

Easy to download libraries

•••
Comes with built in build tool called "mix". This will automatically download libraries and put them in the scope of the application when you add them to the "deps" function and run mix deps.get
Endi Sukaj
Gage Peterson
Top Pro

Great getting started tutorials

•••
The tutorials are very clear and concise (even for a person not used to functional programming). Plus they are also very mobile friendly.
Paolo
Endi Sukaj
Gage Peterson
Top Pro

Syntax is similar to Ruby, making it familiar for people used to OOP

•••
All of the benefits of Erlang; without as steep a learning curve of prolog based syntax. Elixir is heavily inspired by Ruby's syntax which many people love.
Matthias Schuster
Top Pro

Full access to Erlang functions

•••
You can call Erlang functions directly without any overhead: https://elixir-lang.org/getting-started/erlang-libraries.html
Matthias Schuster
HumbleCelaeno
Top Pro

Powerful metaprogramming

•••
Write code that writes code with Elixir macros. Macros make metaprogramming possible and define the language itself.
Endi Sukaj
Top Con

Some design choices may seem strange

•••
Some design choices could have been a little more appealing, for example: using "do...end" comes natural in Ruby for blocks but Elixir uses them for everything and it looks pretty weird: Enum.map [1, 2, 3], fn(x) -> x * 2 end or receive do {:hello, msg} -> msg {:world,...
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82

Scheme

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Endi Sukaj
Andris Pelcbergs
Top Pro

Simple syntax

•••
Scheme syntax is extremely regular and easy to pick up. A formal specification of the syntax fits onto just a few pages; it can be introduced informally in a paragraph or two. Students are not distracted by remembering how to write if statements or loops or even operator precedence because every s...
Endi Sukaj
Andris Pelcbergs
Top Pro

Great, well known textbooks available

•••
There is a set of very strong textbooks introducing CS and programming using Scheme. These books are available for free online. The most famous example--and one of the most famous CS books full stop--is Structure and Interpretation of Computer Programs usually known as SICP. This book introduces f...
Endi Sukaj
Andris Pelcbergs
Dave Pawson
Top Pro

Great at teaching fundamental programming ideas

•••
Scheme teaches the important, fundamental ideas immediately without the distraction of unnecessary syntax or language features.
Endi Sukaj
Top Pro

No Magic - it's clear how everything works

•••
Scheme has far less built into the language itself, helping students see that things like OOP are not magical: they are just patterns for organizing code. Everything in Scheme is built up from a very small set of primitives which compose in a natural and intuitive fashion. Having a language that d...
DazzlingKupala
Top Pro

Many different implementations for different domains

•••
There are around 30 different implementations of the most recent Scheme standard (R7RS), optimized for different domains - from embedded systems over native compilation, desktop programs, web services and the JVM up to targeting Javascript in Browsers.
DazzlingKupala
Top Pro

Multiparadigm

•••
Unlike most languages, Scheme actually accords both functional programming and imperative programming roughly equal status. Many other languages like Python and Java are staunchly imperative while SML and Haskell are primarily functional; Scheme is a nice middle ground. Additionally, since Scheme...
Endi Sukaj
DazzlingKupala
Top Pro

Great, well known textbooks

•••
There is a set of very strong textbooks introducing CS and programming using Scheme. These books are available for free online. The most famous example--and one of the most famous CS books --is Structure and Interpretation of Computer Programs usually known as SICP. This book introduces fundament...
ShrewdNunbarsegunu
Top Con

Fragmented ecosystem

•••
Scheme is an IEEE standard, not an implementation. Unfortunately, the standard is too minimal and practical implementations have diverged--they had to expand on the standard to get anything done, but did so in incompatible ways. The later de facto standard R6RS tried to correct this, but lost Sch...
Endi Sukaj
Andris Pelcbergs
Top Con

Not purely functional

•••
Scheme is a multi-paradigm language including metaprogramming and procedural elements alongside functional elements. As such it will not give a clear impression of a purely functional language.
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74

F#

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Endi Sukaj
Tony
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.
Tony
Top Pro

Easier transition from other paradigms

•••
Since F# is not a purely functional language, it lends itself to being more easily picked up by programmers that have experience with other paradigms.
Endi Sukaj
Andris Pelcbergs
Tony
Top Pro

.NET Interoperability

•••
Since F# runs on the Common Language Runtime or CLR, it has access to the entire .NET Framework, as well as libraries written in other .NET languages such as C#, VB.NET, and C++/CLI.
Andris Pelcbergs
Kribbel
Top Pro

Natively supported by Visual Studio

•••
This is a .Net language natively supported by Visual Studio. Though it is not as tooled up as C# the support is still substantial. In particular, C# deployment scenarios can be enabled for it with small C# wrapper projects. Integration with Visual Studio provides: IntelliSense, debugging, projects...
rystrm
Top Pro

Multiplatform, it runs on .Net Core

•••
Forget Xamarin and Mono. F# now runs on the multiplatform .Net Core!
WhiteLilac
Mangel Maxime
Top Pro

You can run F# in the browser

•••
Thanks to a project like Fable, you can write and run your client app in F# and run it over JavaScript. It allows you to share code between your server and client.
thermoplastics
Tom7
Top Pro

F# is supported by Xamarin

•••
Thanks to Xamarin, F# is a functional language that you can use to build for iOS, Android and Windows.
Matthew Chudleigh
Top Pro

Fall into the pit of success

•••
F# directs you into a workflow where the right way is the path of least resistance. Coming from a C# background, its restrictions might feel arbitrary at first (e.g., what do you mean my code has to be in dependency order!? Arbitrary alphabetical or bust!), but you'll soon realize that your co...
Laura Kyle
rystrm
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 7 more ProsSee 7 more Pros
74

Racket

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Marc Telesha
Top Pro

Free Resources to Learn

•••
Includes several free online books and great documentation.
Endi Sukaj
Marc Telesha
Top Pro

Racket was designed to teach functional programming from the start

•••
Racket is based on Scheme (LISP Family) and is very similar to Clojure. So there are a ton of (). The reason it is easier to learn is that it is not trying to be "Pure" if there is even such a thing in terms of Functional Programming. The great thing about Racket is it has everything incl...
Jonathan
Mario T. Lanza
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.
Endi Sukaj
Top Pro

Easily embeddable

•••
Racket is famously embedded in the game engine underlying Naughty Dog's Uncharted and The Last of Us games, because it proved to be so easy to embed.
Marc Telesha
Top Pro

Great RPEL IDEA included Dr. Racket

•••
Endi Sukaj
Top Pro

Active community

•••
Racket has an active community of users/developers that makes it easy to get help when needed.
Know any negative aspects of this option?
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--

OCaml

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Kristaps
Oleg Tsyba
Top Pro

Encourages functional style

•••
It steers you towards a functional style, but doesn't bother you with purity and "monads everywhere" like other languages, such as Haskell.
robla
Endi Sukaj
Max Strobel
Top Pro

Actively-developed functional programming language at the forefront of research

•••
Functional programming is based on the lambda calculus. OCaml is in its functional parts almost pure lambda calculus, in a very practical manner: useful for many daily programming tasks. The acitve development makes improvements to the type system like generalized algebraic data types (GADT) or pol...
Endi Sukaj
Mohammad Reza Hajianpour
Top Pro

Sophisticated and easy-to-use package manager

•••
OPAM is a package manager for OCaml, which is really easy to use, just like npm. It creates a .opam folder in home directory. The documentation is great as well, and you can switch between multiple versions of OCaml for each project. You can also package your project and publish it on OPAM reposi...
Jonathan
Mohammad Reza Hajianpour
Top Pro

One of the best for writing compilers

•••
OCaml is compiled to native binary, so it's amazingly fast. Being a member of ML-family languages, it has expressive syntax for trees, and has great LLVM support.
Endi Sukaj
Bramford
Top Pro

Strong editor integration

•••
The merlin editor tool provides all you need to develop OCaml in your favourite editor.
Endi Sukaj
Max Strobel
Top Con

Strong focus on *nix systems, lacking native support for MS Windows

•••
Lacks native support for Windows systems.
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Idris

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Jonathan
Top Pro

Full dependent types

•••
Idris not only has support for type classes, but is a fully dependently typed language, giving you the full power to statically verify your code.
Jonathan
Top Pro

Domain driven design and type driven development

•••
Because of full dependent types in Idris, the programmer can focus more on modelling the domain with types and waste less time fixing common bugs that the type checker will catch. Dependent types help apply type driven development and a lot of code auto generation, making the compiler and type che...
Endi Sukaj
Steven Sagaert
Top Con

The language is still under development

•••
Jonathan
Top Con

Different semantics from Haskell

•••
Idris, while similar to Haskell, has strict semantics, which may cause some confusion if your backend is done in Haskell. If using Idris, it would make sense to do the backend in Idris as well, if not for the fact that Idris currently has fewer libraries available for web development than Haskell.
Jonathan
Top Con

Weaker type inference

•••
As type inference is undecidable for dependently-typed languages, Idris cannot offer the full type inference that Haskell supports, and so more type annotations will be needed.
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62

Scala

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Endi Sukaj
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.
Endi Sukaj
Andris Pelcbergs
Peter Zeller
Top Pro

Supports both Functional and OOP paradigms

•••
Scala supports both Functional and Object Oriented styles of programming. Beginners can learn both paradigms without having to learn a new language, and experts can switch between the two according to what best suits their needs at the time.
Endi Sukaj
Top Pro

Great for concurrency

•••
The immutable values make it perfect for working with concurrency.
Endi Sukaj
Luben Karavelov
Top Pro

Powerful static type system

•••
It make easy to create complex abstractions and statically guarantee the safety of your program
Endi Sukaj
Top Pro

Offers type inference

•••
Scala offers type inference, which, while giving the same safety as Java's type system, allows programmers to focus on the code itself, rather than on updating type annotations.
Kristaps
김태근
Top Pro

Great REPL

•••
It makes it easy to practice or test code.
Tom Raleigh
Top Con

Limited type inference

•••
Compared to other languages with type inference, such as Haskell, Scala's implementation is quite limited
Endi Sukaj
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.
Endi Sukaj
Steven Sagaert
Top Con

All the object-oriented constructs distract from learning functional programming concepts

•••
It's not a "functional only" or even a "functional first" language. It 's very heavily object-oriented and all the functional concepts are implemented via OOP constructs or have to be implemented by the programming via those OOP construct (patterns). This makes it way mo...
Maris Orbidans
Top Con

Static type system inherits cruft from Java

•••
The type system is too complicated yet still less powerful than Haskell's.
Maris Orbidans
Top Con

Way too complex for beginners

•••
Even for seasoned programmers it's a difficult language.
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--

Kotlin

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Endi Sukaj
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...
Endi Sukaj
Top Pro

Easy adoption for existing Java programmers

•••
Kotlin runs on the JVM and Java interoperability has been one of the main objectives since the language was born. It runs everywhere Java does; web servers, mobile devices (Android), and desktop applications. It also works with all the major tools in the Java ecosystem like Eclipse, IntelliJ, Mave...
Endi Sukaj
Top Pro

Easy to learn if you have prior programming experience

•••
Kotlin's syntax is extremely easy to understand. The language can be picked up in a few hours just by reading the language reference.
Endi Sukaj
Top Pro

No runtime overhead

•••
The standard library is relatively small and tight. It mostly consists of focused extensions of the Java standard library and as such adds no additional runtime overhead to existing Java projects.
Endi Sukaj
Top Pro

Officially supported for Android development

•••
Starting with version 3.0 of Android Studio, Kotlin support will be built-in. This means that it's now easier than ever to use Kotlin for existing Android projects or even start writing Android apps only with Kotlin from scratch. This also means that Kotlin and Kotlin plugins for Android Stud...
Endi Sukaj
Top Pro

Low-risk adoption for existing Java codebases

•••
Since it has such a good interoperability with Java, Java libraries, and Java tools. It can be adopted for an existing Java codebase at little to no cost. The codebase can be converted from Java to Kotlin little by little without ever disrupting the functionality of the application itself.
Endi Sukaj
Top Pro

Does not impose a particular philosophy of programming

•••
It's not overly OOP like Java and it does not enforce strict functional paradigms either.
Endi Sukaj
Top Pro

Is built to solve industrial problems

•••
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 h...
Endi Sukaj
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.
Endi Sukaj
Top Con

The need for Java interoperability has forced some limitations

•••
The need to make Kotlin interoperable with Java has caused some unintuitive limitations to the language design.
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--

Ceylon

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Roland Tepp
Top Pro

Excellent type system

•••
Intersection and union types make expressing some concepts very easy and intuitive
Roland Tepp
Top Pro

Regular syntax

•••
Makes it very easy to parse and read code
Endi Sukaj
Roland Tepp
Top Pro

Local type inference

•••
Removes a lot of boilerplate
Endi Sukaj
Gavin King
Top Pro

Great support for processing lazy streams

•••
Ceylon has great support for processing lazy streams using higher order functions and comprehensions.
Endi Sukaj
Steven Sagaert
Top Con

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

•••
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55

Python

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Billy “Neceros” Barnes
Top Pro

Easy to use

•••
Jonathan
Billy “Neceros” Barnes
Top Pro

Applications or web-based

•••
Can be used in both OS and web-based environments very well.
Billy “Neceros” Barnes
Top Pro

Fast

•••
Billy “Neceros” Barnes
Top Pro

Powerful full functional language

•••
Endi Sukaj
Marc Telesha
Top Con

Not designed for functional programming

•••
Bare minimal list functions and no tail recursions. Biggest hangup is the imperative syntax which makes it difficult to make it have weak expressions.
gilch
Top Con

Multiparadigm

•••
While Python has powerful enough features to do functional programming, this is not required or even Pythonic (i.e. idiomatic for Python code). Unless you have a text or course specifically designed to teach the functional style in Python, learning Python really won't teach it.
greyfade
Top Con

*Not* a fully functional language

•••
Python is missing several features that make it fully functional, and has several design issues that make pure-functional programming a chore at best. The biggest of these is the limitations of lambdas and dysfunctional closure scoping.
Billy “Neceros” Barnes
Top Con

Slightly slower

•••
When microseconds are involved and very high data throughput, python can respond slower than a base C/C++ application. But not very much.
alphajuliet
Top Con

Inelegant and messy language design

•••
The first impression given by well-chosen Python sample code is quite attractive. However, very soon a lack of unifying philosophy / theory behind the language starts to show more and more. This includes issues with OOP such as lack of consistency in the use of object methods vs. functions (e.g.,...
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55

Erlang

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Endi Sukaj
Top Pro

Fault-tolerant

•••
Fault tolerance means that a system has the property to continue operating even though one or more components have failed. For Erlang systems, this means that the system is kept running even if for example a user has to drop a phone call rather than forcing everyone else to do so. In order to ach...
Endi Sukaj
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...
Endi Sukaj
Top Pro

Great for writing distributed applications

•••
Erlang is made to be parallel and distributed. Because it's very easy to write code that uses multiple processor cores, it's also very easy to write applications that span multiple servers.
Endi Sukaj
Top Pro

Upgrade code without stopping the system

•••
In a real-time system it may not be possible to stop the system in order to implement code upgrades. For these cases Erlang gives you dynamic code upgrade support for free when using OTP. The mechanism is very easy to understand and works as follows: Start the app Edit the code Recompi...
Endi Sukaj
Top Pro

Built from the ground up with concurrency and distributed computing in mind

•••
Erlang has strong roots with the telecom industry in which concurrent processes are normal. It's designed to be concurrent, to be used for distributed computing and to be scalable.
Endi Sukaj
Top Pro

Little overhead

•••
Erlang's processes have very little overhead (about 500 bytes per process). This means that a huge amount of processes can be created, even on older machines.
Endi Sukaj
Top Pro

Consistency across platforms

•••
Erlang's processes run in a complete independent way from the OS (they aren't managed by the OS scheduler neither). This means that programs written in Erlang will run exactly the same way regardless of the operating system or platform.
Endi Sukaj
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.
Endi Sukaj
Top Con

Useful in only one niche

•••
Erlang is not really a general purpose language. It has a very special and well-defined niche where it towers above everything else. It's specialized in scalability and in distributed applications. Which is not necessarily a bad thing per se, but it still lacks and falls behind other languages...
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--

Standard ML

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Endi Sukaj
Top Pro

Powerful module system

•••
The module system that Standard ML uses gives the programmer the power to define custom data types whose internal implementation is invisible to other programmers using the module.
Endi Sukaj
Top Pro

Implementing laziness is trivial

•••
Since mutability is only confined to a special type of reference cells, implementing laziness in SML can be done in only 20 lines of code.
Andris Pelcbergs
Endi Sukaj
Top Pro

Enforces distinction between data and computations

•••
Since it uses strict evaluation, it enforces distinction between data and computations which in turn enables you to use induction on algebraic data types as a reasoning principle.
Endi Sukaj
Top Pro

Great exception system

•••
Secret messages can be sent across distant parts of a program without possibility of being intercepted by unintended recipients in the middle.
Endi Sukaj
Top Con

Not very popular outside academia

•••
SML is mostly used in academia and doesn't have many uses in industry. While it's a good language for learning functional programming concepts, the language itself won't be very useful.
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--

PureScript

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alphajuliet
Top Pro

Pure functional language

•••
You cannot have side effects, unless a function is explicitly defined as so.
alphajuliet
Top Pro

Type safety

•••
Compiling should be your first unit test. A tight type system (static and hopefully strong) will catch many logic errors that are often difficult to spot through debugging. In languages like PureScript, if it compiles, it often runs properly.
alphajuliet
Top Pro

Modules can be compiled to CommonJS 

•••
Modules compiled to CommonJS can be included with 'require', making it incredibly simple to call Purescript code from Javascript.
Paolo
alphajuliet
Top Pro

Higher kinded types

•••
Has Typeclasses and RankNTypes.
Know any negative aspects of this option?
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--

Nim

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Belle
Top Pro

Really crossplatform

•••
The same code can be used for web, server, desktop and mobile.
Belle
Top Pro

Multi-paradigm

•••
Imperative, OOP, functional programming in one language.
Belle
Top Pro

Strict typing

•••
Checks your code at compile time.
Belle
Top Con

Still in pre 1.0

•••
The same code can be used for web, server, desktop and mobile.
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--

Oz

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thermoplastics
gilch
Top Pro

Concepts, techniques, and models of computer programming

•••
CTM teaches all the major paradigms with mathematical rigor, including functional programming.
Know any negative aspects of this option?
--

J

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Pascal J
Top Pro

25 year old language, with core unchanged in last 10 years

•••
Still actively developed, but most recent changes have been in libraries and IDE and platform support. Language is considered "perfected"... though not quite.
Endi Sukaj
Pascal J
Top Pro

Simpler Imperative language constructs as failback to functional programming

•••
J also supports multiline functional definitions similar to BASIC/Pascal. Including error handling.
Pascal J
Top Pro

Compiled language speed from interpreted language.

•••
Each built in operator is a C/asm function, and special code further optimizes some operator combinations. Result is optimized C speed from quick parsing. Array orientation parses and compiles a function once, and applies it to all array items.
Pascal J
Top Pro

Language reference has simple one page index

•••
Complete core programming functional tools allow writting programs and libraries without imports.
Pascal J
Top Pro

No operator precedence rules

•••
(... within each of the 3 operator classes) makes reading code easier. Very simple parsing rules.
Pascal J
Top Pro

Every function is an operator

•••
3 classes of operators (verbs, adverbs, and conjunctions) with verbs the most basic function that take either 1 or 2 (infix) parameters. Operators allow function composition with a minimum of parentheses.
Charles Perng
Top Con

Syntax is pure madness

•••
quicksort=: (($:@(<#[), (=#[), $:@(>#[)) ({~ ?@#)) ^: (1<#)
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--

Groovy

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Java

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Endi Sukaj
Green Harry
Top Pro

Java - a functional programming language

•••
Java is hostile to functional programming. If you write Java code that has no side-effects, that doesn't read or change the local object's state. That's not how Java is written. Your side-effect free code will be peppered with static keywords, and they'll frown and drive you out of...
Laura Kyle
Grygorii Kvasha
Top Con

Not really functional

•••
Doesn't help in learning FP in any way.
Endi Sukaj
Emrul Zawad
Top Con

Too verbose

•••
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513 Community Recommendations

Fabián Heredia Montiel
Eugene A. Simonenko
gilch
Gage Peterson
Oleg Tsyba
Mark Elston
Mario T. Lanza
schlaumeier
Emanuel Goette
Maris Orbidans
Bill Christian
+311
Request recommendations from the community
joseph stevens
joseph
Contributor for 3 months
2
Total 
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100
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Elm
Recommended 3 months ago
6 months, after two years of F# with limited progress in learning functional programming, elm taught me in two months. Elm is simple on purpose, and pure.
Pro
 Avoids advanced FP topics such as Monads
Pro
 Compile errors are human-friendly
Pro
 No run-time exceptions
See full
mailinator
mailinator
Contributor for 3 years
20
Total 
Recs.
2.5K
Total 
Karma
Elm
Recommended 4 months ago
much better than trying to make javascript do functional code
Pro
 The Elm architecture offers a simple pattern for all programs
Pro
 Avoids advanced FP topics such as Monads
Pro
 Compile errors are human-friendly
Pro
 Easier to make front ends than JS
Pro
 No run-time exceptions
See full
Ernesto Barros
Ernesto
Contributor for 2 years
3
Total 
Recs.
0
Total 
Karma
F#
Recommended 6 months ago
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!!
Pro
 .NET Interoperability
Pro
 Easier transition from other paradigms
Pro
 Concise syntax
Pro
 Natively supported by Visual Studio
Pro
 F# is supported by Xamarin
Pro
 Multiplatform, it runs on .Net Core
Pro
 You can run F# in the browser
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