Index - Erlang/OTP

fact(0) -> 1; %% Pattern matching for control-flow fact(N) -> N * fact(N-1). %% Recursion to create loops > example:fact(10). %% Interactive shell for fast iterations 3628800 > [{I, example:fact(I)} || I <- lists:seq(1,10)]. [{1, 1}, {2, 2}, {3, 6}, {4, 24}, {5, 120}, {6, 720}, {7, 5040}, {8, 40320}, {9, 362880}, {10, 3628800}]

> Fruits = ["banana","monkey","jungle"]. %% Immutable variables ["banana","monkey","jungle"] > lists:map(fun string:uppercase/1, Fruits). %% Map values using stdlib functions ["BANANA","MONKEY","JUNGLE"] %% Fold over lists using custom functions > lists:foldl(fun(Str, Cnt) -> string:length(Str) + Cnt end, 0, Fruits). 18

> Parent = self(). %% Get own process id <0.376.0> > Child = spawn(fun() -> receive go -> Parent ! lists:seq(1,100) end end). <0.930.0> > Child ! go. %% Send message to child go > receive Reply -> Reply end. %% Receive response from child [1,2,3,4,5,6,7,8,9,10,11|...]

-spec even(list(integer())) -> list(integer()). even(Numbers) -> mapreduce(Numbers, fun(Number) -> Number rem 2 == 0 end). mapreduce(Numbers, Function) -> Parent = self(), [spawn(fun() -> Parent ! {Number, Function(Number)} end) || Number <- Numbers], lists:flatten( [receive {Number, true} -> Number; _ -> [] end || Number <- Numbers]).

What is Erlang?

Erlang is a programming language used to build massively scalable soft real-time systems with requirements on high availability. Some of its uses are in telecoms, banking, e-commerce, computer telephony and instant messaging. Erlang's runtime system has built-in support for concurrency, distribution and fault tolerance.

Erlang Quickstart

What is OTP?

OTP is set of Erlang libraries and design principles providing middle-ware to develop these systems. It includes its own distributed database, applications to interface towards other languages, debugging and release handling tools.

Getting Started with OTP

News

Erlang/OTP 29 Highlights May 18, 2026 by Björn Gustavsson: Erlang/OTP 29 is finally here. This blog post introduces the new features that we are most excited about.
Erlang/OTP 29.0 May 13, 2026 by Henrik Nord: Erlang/OTP 29.0
Erlang/OTP 28.5 Release April 23, 2026 by Henrik Nord: Erlang/OTP 28.5 is the fourth maintenance patch package for OTP 28, with mostly bug fixes.

Practical functional programming
for a parallel world

What is Erlang?

What is OTP?

News

Erlang/OTP 29 Highlights

Erlang/OTP 29.0

Erlang/OTP 28.5 Release

Participate

Practical functional programming for a parallel world

What is Erlang?

What is OTP?

News

Erlang/OTP 29 Highlights

Erlang/OTP 29.0

Erlang/OTP 28.5 Release

Participate

Practical functional programming
for a parallel world