true`, `false`, and `ok`.IEEE 754 standard.{}`. They can store elements of different data types and are often used to group related values together. For example, `{1, "hello", true}` is a tuple with three elements.[]`. They are often used to represent sequences of data. Erlang lists are linked lists and can contain elements of any data type. For example, `[1, 2, 3]` is a list of integers.
5. Binaries : Binaries are sequences of bits or bytes enclosed in `<<>>`. They are used to represent binary data and are commonly used for handling network protocols, file I/O, and encoding/decoding operations.hello"` is represented as the list `[104, 101, 108, 108, 111]`.erlang:disconnect_node/1` function. The syntax is as follows:erlang:disconnect_node(Node).​Node` is an atom representing the name of the node you want to disconnect from the current node's cluster.'othernode@localhost'`, you would use the following command:erlang:disconnect_node('othernode@localhost').​spawn/1` or `spawn/3` functions. Each process is identified by a unique process identifier (PID).!` operator. For example, `PID ! Message` sends `Message` to the process identified by `PID`. The sender does not wait for a response but continues its execution immediately.receive` construct. It allows a process to wait for specific messages and pattern match on the received messages to determine the appropriate action to take.receive` block. Messages that match a pattern are processed, while non-matching messages remain in the process's mailbox until a matching pattern is encountered.
5. Selective Receive : Erlang provides selective receive, which allows processes to prioritize specific messages over others. By specifying different patterns in the receive block, processes can selectively handle certain messages based on their content or structure.module` attribute at the beginning of an Erlang source file. The module attribute specifies the name of the module, which must match the filename. For example, a module named `my_module` should be defined in a file named `my_module.erl`.export` attribute, specific functions within a module are marked as "exported," indicating that they are intended to be used by other parts of the system.import` attribute. Importing a module allows access to its functions without explicitly qualifying them with the module name. io:format/2` or `dbg:tracer/0`. These statements print out values or messages at specific points in your code, allowing you to track the flow and values of variables during execution.dbg`. It allows you to set breakpoints, trace function calls, and inspect the state of processes during runtime. You can start the debugger using `dbg:tracer/0` and use functions like `dbg:tp/2` to set trace patterns.error_logger` module provides functions such as `error_logger:error_msg/2` to generate error logs. These logs can be examined to pinpoint the source of errors and understand the program flow.eunit` framework is commonly used in Erlang for unit testing. Running tests and examining the test results can help identify issues and validate the correctness of the code.et` module in Erlang provides a low-level tracing facility that allows you to trace the execution of specific processes or functions. It provides fine-grained control over tracing and can be useful for analyzing complex or performance-critical code..dump) when a process crashes. These dump files contain valuable information about the state of the system at the time of the crash, including process stacks, registered processes, and heap information. Analyzing these crash dumps can provide insights into the cause of the crash.recon`, `observer`, and `fprof`, to gather information about the runtime behavior, process activities, memory usage, and performance characteristics of your Erlang system. These tools can assist in identifying bottlenecks, resource leaks, and performance issues. actors" that communicate via message passing. Erlang, being inspired by the actor model, implements its own version of actors to enable concurrent and distributed programming..beam". When an Erlang module is compiled, the Erlang compiler (erlc) transforms the source code into bytecode that can be executed by the Erlang virtual machine (BEAM)..beam files) contain the compiled code for the module's functions, as well as metadata and other information related to the module. This bytecode format is specific to Erlang and is not directly readable or editable by developers..beam files have the same name as the Erlang module they represent, with the ".beam" extension..beam files into memory. This allows the functions and code within the modules to be accessed and executed during runtime..beam file. The new .beam file can then be loaded by the Erlang virtual machine to incorporate the changes made to the module's code. spawn/1` or `spawn/3` functions.spawn/1` or `spawn/3` function is used, which takes a function as an argument. The specified function defines the behavior and logic of the process. The `spawn/1` function takes a single argument, the function that will be executed by the process, while the `spawn/3` function allows passing additional arguments to the function.
Here's an example of creating a user process in Erlang :start_process() ->
Pid = spawn(fun() ->
% Process behavior and logic here
io:format("Hello from process!~n")
end),
Pid.​spawn/1` function is used to create a new user process. The anonymous function passed as an argument will be executed by the newly created process. The `io:format/1` function is called within the process to print a message.Pid` variable captures the process identifier (PID) of the newly created process, which can be used to communicate with or monitor the process. !` operator for message passing is not limited to processes within the same node but can be used to send messages between processes residing on different nodes. The message passing mechanism remains the same regardless of whether the processes are local or remote.net_adm:ping/1` and `net_adm:world/0` to manage connectivity and discover other nodes in the distributed system. Nodes can be manually connected by specifying the names or IP addresses of other nodes, or they can automatically discover and connect to neighboring nodes using the `net_kernel` application.global` module. Processes can be registered with a unique name that is accessible from any node in the distributed system. This allows processes on different nodes to refer to each other by registered names, facilitating communication and coordination.erlang:monitor_node/2` and receive notifications in case of node failures. When a node connection is lost, Erlang provides facilities to handle the situation, such as performing cleanup actions or initiating failover procedures.riak_core` that allow for distributed and fault-tolerant storage of data across multiple nodes. These storage options provide features like data replication, partitioning, and consistency guarantees to ensure data availability and fault tolerance. << >>`) and consist of a sequence of bits or bytes.AND, OR, XOR, NOT), shift bits, set specific bits to 0 or 1, extract or match specific bit patterns, and more.spawn/1` or `spawn/3` functions. When a process is created, it is assigned a unique PID that can be used to interact with the process.
4. PID Usage : PIDs are primarily used for process communication and process monitoring in Erlang. They serve as the destination for sending messages using the `!` (message passing) operator. PIDs can also be used to establish links between processes, allowing them to monitor each other's status and receive notifications in case of process termination or failure.<0.X.Y>`, where X represents the Serial number and Y represents the Creation number. The initial number `0` indicates that the process resides on the local node.<0.123.0>`123`, Creation number `0`, and residing on the local node. !` (Bang or exclamation mark operator) :!` operator is the basic message sending primitive in Erlang. It is used to send a message from one process to another. The syntax for sending a message is `SenderPid ! Message`, where `SenderPid` is the process identifier (PID) of the sending process, and `Message` is the data to be sent. The message is sent asynchronously, meaning the sending process does not wait for a response. The message is delivered to the recipient's mailbox for later processing. ReceiverPid ! {self(), "Hello, world!"}.​receive` block :receive` block is used by processes to receive and handle incoming messages. It allows a process to wait for specific messages and pattern match on the received messages to perform different actions. The syntax of a `receive` block is as follows: receive
Pattern1 [when Guard1] -> Action1;
Pattern2 [when Guard2] -> Action2;
...
PatternN [when GuardN] -> ActionN
end​ receive
{SenderPid, Message} -> io:format("Received message: ~p~n", [Message])
end.​{SenderPid, Message}` and then prints the received message.Erlang processes," which are not tied to operating system threads. Here's how Erlang achieves concurrency without locks or traditional threads:!` operator. Message passing in Erlang is non-blocking, meaning the sender doesn't wait for a response. Processes can concurrently send and receive messages, enabling asynchronous and concurrent communication without the need for locks..erl` extension. When an Erlang system starts, it loads the necessary modules into memory.gen_tcp` and `gen_udp` modules provide abstractions for working with TCP and UDP sockets, respectively. These modules allow you to create, bind, connect, send, and receive data over network sockets. You can open multiple sockets and handle concurrent communication with different clients or servers.gen_tcp:listen/2` to listen for incoming connections, `gen_tcp:accept/1` to accept incoming connections and create new sockets for communication, `gen_tcp:connect/3` to establish a connection to a remote server, and `gen_tcp:send/2` and `gen_tcp:recv/3` for sending and receiving data over TCP sockets.gen_tcp` and `gen_udp` modules to receive and handle messages asynchronously. The `inet` module provides functions to convert between Erlang terms and network byte orders.
ssl` module enables secure socket communication using the Secure Sockets Layer (SSL) or Transport Layer Security (TLS) protocols.gen_server`, `gen_fsm`, and `gen_event`, can be used to build networked applications by encapsulating socket communication and providing abstractions for handling connections, managing states, and handling message passing between processes. <<>>`) that allows you to store and manipulate binary data efficiently. Unlike lists, binary data in Erlang is stored as a contiguous block of memory, reducing memory overhead and enabling efficient processing.<<>>`) provide a concise and efficient way to transform, filter, and manipulate binary data. They allow you to perform pattern matching and extraction operations directly on binary data, avoiding the need for explicit copying or conversion.<<>>` syntax with offset and length specifications, you can create lightweight references to specific portions of the original binary. This allows you to operate on specific segments of large binary data without duplicating it.
* Binary Copying and Fragmentation : When performing operations that modify binary data, such as concatenation or substring extraction, be cautious of unnecessary copying and fragmentation. Erlang performs binary copying when necessary, so it's important to minimize unnecessary operations that involve copying or manipulating large binary data frequently.C or C++ code to handle binary data operations, achieving high performance when working with large volumes of data. hibernated" to a disk file, freeing up system resources while preserving its state. The hibernated process can later be resumed from the disk file, allowing it to continue execution from where it left off. gen_server` behavior in Erlang is a part of the OTP (Open Telecom Platform) framework and provides a standardized approach for building server processes. It offers a set of behaviors, callbacks, and utilities that simplify the implementation of concurrent, stateful server processes in Erlang. The purpose of the `gen_server` behavior is to facilitate the development of reliable, fault-tolerant, and scalable server processes with a consistent structure and behavior.gen_server` behavior :gen_server` behavior defines a standardized structure for server processes, making it easier to understand and maintain code. It provides a clear separation of concerns by separating the initialization, request handling, and termination logic into distinct callback functions.gen_server` behavior allows multiple client processes to send requests concurrently to the server process. It handles the message passing and queueing of requests, ensuring that messages are processed one at a time in a serialized manner, maintaining the consistency of the server's state.gen_server` behavior provides a convenient mechanism for managing and updating the server's state. The server process can maintain its state internally, and the behavior provides callback functions, such as `handle_call` and `handle_cast`, for handling incoming requests and asynchronous messages. These callbacks define how the server's state is updated and how responses are sent back to the client processes.
4. Error Handling and Fault Tolerance : The `gen_server` behavior supports fault tolerance through its error handling mechanisms. It provides a `handle_info` callback for handling system messages, allowing the server process to respond to errors, timeouts, and other events. The behavior also supports supervision, allowing the server process to be monitored and restarted in case of failures.gen_server` behavior allows both synchronous and asynchronous communication between the server process and client processes. Client processes can send synchronous requests and wait for a response, or they can send asynchronous requests without waiting for a response. This flexibility enables different interaction patterns and caters to various application requirements.gen_server` behavior integrates well with Erlang's hot code swapping capability. It supports code upgrades, allowing server processes to seamlessly transition from an old version of the code to a new one without interrupting the service. This is essential for maintaining high availability and system uptime.