Erlang (programming language)/Tutorials

Erlang Language Programming Tutorials

Syntax of functions

Functions are defined by the domain of the arguments and the number of arguemnts. A function ends with a period. A function defined over differnt domains are separated by semicolons. A fact function gives an answer that is sensitive to the domain of the input. With strings it gives a fact. With counting numbers it gives the factorial function.

fact("aloha") -> "Aloha is a greating";
fact(String) when is_a_list(String) -> 
    "no fact is known about " ++ String;
fact(0) -> 1;
fact(N) when is_integer(N) and (N > 0) -> 
    fact(N-1)*N;
fact(N) when N < 0 -> error.

Macros

-define(LIKERT_SCALE, lists:seq(1, 5)).

A = LIKERT_SCALE.

Regular Expressions

Regular Expressions

2> regexp:match("hello world","w.+d").
{match,7,5}

The regular expression, "w.+d" matches the string, "hello world" at location 7 for 5 chars.

9> regexp:sub("10203040","([2|3|4]0)+","01").
{ok,"1001",1}

Makes a substitution, replacing "203040" with "01".

Examples

Hello World (serial)

Code Example

-module(hello).
-export([start/0]).

start() ->
   io:format("Hello, world!\n").

Analysis of the example

The Hello World program (see above) appears in many programming languages books and articles as a cursory introduction into a language's syntax. The first hello world program was introduced in the book The C Programming Language.

-module(hello) tells the compiler to create a new module(library) called hello. The code tells us the file name for this code: hello.erl.

-export([start/0]). exports a function named start with 0 arguments to the world outside of this module called hello.

start() -> tells the compiler that there is a function named start() with no arguments.

io:format("Hello, world!\n"). will make the program output Hello, world! and a new line (\n) on the screen.

Hello World (parallel)

Parallel Hello

Prime Sieve (parallel with linda type coordination)

Prime Sieve with Linda

Autonomous Agents

Autonomous Agents in Erlang

See definition of Autonomous Agent.

Advanced OTP

ETS

ETS programming

References

1 - Erlang Man Pages at Erlang,org