Learn Erlang through this set of challenges. An interactive system for getting to know Erlang.
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Erlang Quest is a small game in which you solve Erlang programming tasks, beginning with very simple stuff.

Erlang Quest is a way to practise Erlang -- writing and problem solving in Erlang.

It does not include tutorials in the syntax etc. of Erlang -- there are plenty of introductory material freely available on the internet (1, 2, 3) Nor does it do much in the way of teaching the standard libraries (4, 5), expect for giving hints about how tasks can be solved (the hint system is not there yet, though). However, it can be used for practising, to learn how to use the standard libraries in practical problem solving.

Questions, feedback, and general discussions will be very much appreciated. You can either use GitHub issues, or post on the Erlang Quest google group.

How to use

The Quest game can be played in two ways: you can play it by yourself (single-user mode), or it can be played by many player at once, each trying to solve the problems and gain points (multi-user mode).

The latter can be used as part of for course-like settings; each participant can then progress in their own pace.

Quick start single-user mode

  make start-server
  > quest:help().

For more information go to the 'How to Play' section.

Quick start multi-user mode

  MY_IP=... make start-server
  MY_IP=... SERVER_IP=... make start-client
  > quest:help().

See right below for more details.

How to set up the server

The steps are as follows (assuming you have Erlang and Git installed):

  • Obtain the ErlangQuest source code: git clone git://github.com/eriksoe/ErlangQuest.git cd ErlangQuest/
  • Build it: make
  • Start the server: make start-server or, for playing from other computers in the network: MY_IP=insert-your-IP-address-here make start-server

This will start an Erlang node with the quest server running, and also with an Erlang interactive shell.

How to connect

For single-player use, you can use the Erlang shell of the node where the server is also running.

For playing from another computer,do:

MY_IP=insert-your-IP SERVER_IP=insert-server-IP  make start-client

Alternatively, start an Erlang shell of your own with the parameters -name somename@insert-your-IP -setcookie questcookie

then connect to the server nodes thus: net_adm:ping('quests@insert-the-server-IP').

How to play

As a player, the most important command to know is

> quest:help().

which does a bit of explaining.

Basically, what you do is

> quest:list(usr).

(if your username is usr) to see what quests are available to you. There may be more quests, but hidden from you until you gain enough points.

Next, you ask for a description of a quest (here the one called 'any_answer'):

> quest:describe_quest(any_answer).
Quest 'any_answer':                            (Worth: 1.  Requires: 0.)
  Answer with any value whatsoever.


This shows what the quest is about, as well as how many points can be gained by solving it (here 1), and how many points you need to have already for the quest to be available to you (here 0).

You can accept a quest in two ways. For solving it manually, do this:

> quest:get_challenge(usr, any_answer).
=> {15776378160770091960,dummy}

There are two elements here: a challenge ID and an input -- the input usually contains the data necessary to solve the quest, but is for this particular quest just a dummy value.

You then answer by:

> quest:answer_challenge(15776378160770091960, any_value).
=> {achievement_unlocked, ...}

The second way of accepting a quest combines these two steps -- of getting and answering a challenge. It involves passing a function which solves the quest to 'quest:submit/2', like this:

> quest:submit(usr, any_answer, fun(_Input) -> any_value end).
=> {achievement_unlocked, ...}

Have fun!

Compiling Solution Code in Modules

After the first couple of quests it might be easier having quest solutions in a module, instead of typing them in the shell.

One way to do this is adding quest solutions to the module in the current directory and then do this:

(quests@> c(eq_solutions).
(quests@> quest:submit(base_7, eq_solutions).

Note, in the example above, quest:submit calls the function eq_solutions:quest_base_7/1, so 'quest_' prefixed with quest name.

Another way (mostly if solutions exists in more than one module) is to use Emake. Create an Emakefile:

pmm@budda:~/projects/ErlangQuest$ cat Emakefile
{"eq_solutions.erl", [debug_info]}.

and then run the following from the shell:

(quests@> make:all([load]).
Recompile: eq_solutions

You can read more on Emake here.

Technical stuff

Only the "quest" module is needed by the players. For multi-player use, it is sufficient to distribute that module, as well as an easy way to start a client node (like the "start-client" Makefile target).