Erlang is a functional programming language created in 1986 by Joe Armstrong at Ericsson. It is known for being highly reliable, concurrent, and modular. Erlang uses lightweight processes instead of threads to handle concurrency. It is dynamically typed and uses pattern matching extensively. Erlang is used in applications like RabbitMQ, CouchDB, Facebook Chat, GitHub, and SimpleDB for its ability to handle large numbers of concurrent connections and its built-in support for distribution and fault tolerance.

1. Erlang

2. What is it?
created by Joe Armstrong in 1986 at Ericcsson Telecom
based on Prolog
functional language
dynamicly typed

3. Erlang is...
reliable
high concurrent (no threads. light processes)
modular

4. Where is it used?
RabbitMQ (France telecom)
CouchDB
Facebook Chat
GitHub (egitd)
SimpleDB (AWS)

5. Types

6. Variables
Var = 2.
Var.
%=> 2
Var = 3. % this throws an error!

7. atoms
this_is_atom

8. Lists
[1,2,3,4]

9. Tuples
{a, 2,"d"}.
{ company,
{name, "Applicake",
{address, "Krakow"}}
}.

10. Matching
Company = {company,
{name, "Applicake"},
{address, "Krakow"}
}.
{company, {name, Name,
{address, Address}}} = Company.
Name %=> "Applicake"
Address %=> "Krakow"

11. Matching
[Head | Tail] = [1,2,3,4].
Head. %=> 1
Tail. %=> [2,3,4]

12. Matching
[One, Two | Rest] = [1,2,3,4].
One. %=> 1
Two. %=> 2
Rest.%=> [3,4]

13. functions
-module(mirror_function).
-export([mirror/1]).
mirror(Argument) -> Argument.

14. functions
-module(matching_function).
-export([number/1]).
number(one) -> 1;
number(two) -> 2;
number(three) -> 3.

15. functions
Numbers = [1,2,3,4].
lists:map(fun(X) -> X+1 end, Numbers).
%=> [2,3,4,5]

16. functions
map(F, [H|T]) -> [F(H) | map(F, T)];
map(F, []) -> [].

17. Control structures
case...
case Animal of
"dog" -> underdoga;
"cat" -> thundercat
_ -> something_else
end.

18. Control structures
if...
if
X > 0 -> positive;
X < 0 -> negative;
true -> zero
end.

19. Processes

20. Processes
Pid = spawn(fun module_name:function_name/0).
Pid ! "message".

21. Processes
fuction_name() ->
receive
"message" ->
io::format("Hi!"),
function_name();
_ ->
io::format("Whatever..."),
function_name()
end.