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![Simple Example -module(recursive). -export([fac/1]). fac(N) when N == 0 -> 1; fac(N) when N > 0 -> N*fac(N-1). fac(0) -> 1; fac(N) when N > 0 -> N*fac(N-1).](https://image.slidesharecdn.com/cslijbqrq4hl8akhughw-signature-a92a8a7b5521333e6b396479f88abdd79383bf86f8b6175abb3822b9ecf50879-poli-180930185319/75/Introduction-to-Erlang-Programming-Language-13-2048.jpg)
Uploaded byYasas Gunarathne
Introduction to Erlang Programming Language
This document provides an overview of the Erlang programming language. It discusses that Erlang is a general purpose, concurrent, functional programming language developed at Ericsson for building distributed, fault-tolerant systems. It notes some of Erlang's key uses in telecommunications, banking, messaging, and e-commerce where high-availability is required. The document also summarizes that Erlang uses processes instead of threads to enable concurrency, and that it relies on recursion rather than loops for iteration due to its functional nature.
Introduction to Erlang Programming Language
- 1. Erlang A concurrent, faulttolerant programming language developed at Ericsson PRESENTED BY Yasas Gunarathne
- 2. What is Erlang? Erlangis a ❖ General-purpose ❖ Concurrent ❖ Functional programming language, as well as a ❖ Garbage-collected runtime system. Wikipedia
- 3. 1. General Purpose? Yes,but It has a very special niche, where it performs extremely well. ➔ Telecommunications and Banking ➔ Instant Messaging ➔ E-Commerce Where ● Distributed, Fault-tolerant, Soft real-time, Readily available, non-stopping applications are required. ● Hot-swapping — allows the code to be modified without stopping the system.
- 4. 2. Concurrent? It iseasy to create parallel threads of execution in an Erlang program and to allow these threads to communicate with each other. In Erlang, each thread of execution is called a process. ➔ Threads of execution in Erlang share no data, that is why they are called processes ➔ There are no DEAD LOCKS or LIVE LOCKS in ERLANG.
- 5. 3. Functional? In afunctional language the assignment of a value to a variable is binding, just as it would be in a mathematical function. In a math example, we might say: let x = 2. That is to say for this problem, x is the value of 2. x = x + 1 Java lambda expression is the Java's first step into functional programming.
- 6. Java Lambda Expressions Eventlisteners in Java are often defined as Java interfaces with a single method. public interface StateChangeListener { public void onStateChange(State oldState, State newState); } In Java 7 we could add an event listener using an anonymous interface implementation.
- 7. Java Lambda Expressions InJava 7 you could add an event listener using an anonymous interface implementation, like this: StateOwner stateOwner = new StateOwner(); stateOwner.addStateListener(new StateChangeListener() { public void onStateChange(State oldState, State newState) { // do something with the old and new state. } }); But in Java 8 we can use lambda expressions...
- 8. Java Lambda Expressions StateOwnerstateOwner = new StateOwner(); stateOwner.addStateListener( (oldState, newState) -> System.out.println("State changed") ); Limitations: ● Does the interface have only one method? ● Does the parameters of the lambda expression match the parameters of the single method? ● Does the return type of the lambda expression match the return type of the single method?
- 9. Erlang Runtime System Erlangprograms are executed when you instruct the Erlang Runtime System (ERTS) to execute your code. They do not run as binary programs, which can be executed directly by your computer. ERTS consists of an Erlang evaluator and some libraries. The Erlang evaluator is often referred to as an emulator and is very similar to the Java virtual machine.
- 10. Built-in Data Types ●Number − In Erlang, there are 2 types of numeric literals which are integers and floats. ● Atom − An atom is a literal, a constant with name. An atom is to be enclosed in single quotes (') if it does not begin with a lower-case letter or if it contains other characters than alphanumeric characters, underscore (_), or @. ● Boolean ● Bit String − A bit string is used to store an area of un-typed memory. ● Tuple ● Map ● List
- 11. Hello World!! % helloworld program -module(hello_world). -export([hello/0]). hello() -> io:fwrite("Hello, world!n"). 1> c(hello_world). 2> hello_world:hello(). Hello, world! ok
- 12. Loops!! loop(0) -> ok; loop(Count)-> % do something loop(Count-1). Functional programming languages don’t offer any constructs for loops. Instead, depends on recursion.
- 13. Simple Example -module(recursive). -export([fac/1]). fac(N) whenN == 0 -> 1; fac(N) when N > 0 -> N*fac(N-1). fac(0) -> 1; fac(N) when N > 0 -> N*fac(N-1).
- 14. Erlang OTP OTP isa collection of useful middleware, libraries, and tools written in Erlang programming language. OTP stands for “Open Telecom Platform”. However neither Erlang nor OTP is specific to telecom applications. If you want to program your own applications using OTP, then the central concept that you will find very useful is the OTP behavior.
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