[erlang-questions] Erlang for youngsters

[Torben Hoffmann]

Anthony Ramine writes:

> Did anyone ever wonder whether Erlang is truly hard to learn, or if it is just how fault-tolerant, concurrent, distributed programming is by definition?
Good question!

I think that fault-tolerant, distributed programming is hard because there is a big
context you need to address. The sheer about of things that can go wrong will make it
difficult to get into.

I think that concurrent programming is easy to learn:

-------------------------------------------------------
I will start teaching your how to program in Erlang by showing you how the
fundamental building block of Erlang, a process works.

A process can receive and send messages. Sending messages is the only way two
processes can communicate.

Here's a simple process that just acknowledges that it has received a message and
continues to do so over and over again:

echo() ->
  receive
    Msg ->
     io:format("I'm happy, 'cause I recevied: ~p~n", [Msg]
  end,
  echo().

The file example1.erl contains the echo function.
Open up the Erlang shell:
$ erl

c(example1).

(this compiles the code and now you can start an echo process)

Pid = spawn ( fun() -> echo() end ).

(you just stored the process identifier (Pid) for the process you spawn, so now you
can send it a message:)

Pid ! "Erlang is cool".

"I'm happy, 'cause I received: Erlang is cool"
-------------------------------------------------------

Then one can add more layers to this, step by step.

Pattern matching can be sneaked in very fast. We already have recursion going for us.
Create a counter process and you have recursion with state data for a process.

For a fresh mind it will be okay to have processes crash. They know of nothing else.

But the key point is still to find a "killer" example that they find motivating.

Cheers,
Torben
-- 
Torben Hoffmann
CTO
Erlang Solutions Ltd.
Tel: +45 25 14 05 38
http://www.erlang-solutions.com