Explain what is epmd?

epmd is a small name server which is used by Erlang programs when establishing distributed Erlang communications. It is also referred as an Erlang Port Mapper Daemon. It is responsible for mapping the symbolic node names to machine addresses it is used.

List out the pre-defined macros in Erlang?

The pre-defined Macros in Erlang is

  • ? Module: It returns the name of the current module
  • ? Module_String: It returns the name of the current module, as a string
  •  ? File: It returns the current file name
  •  ? Line: It returns the current line number
  • ? Machine: It returns the current machine name, ‘BEAM.’

What are the valid guard expressions in Erlang?

Valid guard expressions are

  • The atom true
  • Other constants (terms and bound variables), all regarded as false
  • Calls to the BIFs specified in table Type Test BIFs
  • Term comparisons
  • Arithmetic expressions
  • Boolean expressions
  • Short-circuit expressions (andalso/orelse)

Define guard sequence and what are the valid guard expressions in Erlang?

guard sequence is a sequence of guards, separated by semicolon (;). The guard sequence is true if at least one of the guards is true. (The remaining guards, if any, are not evaluated.)

guard is a sequence of guard expressions, separated by comma (,). The guard is true if all guard expressions evaluate to true.

In Erlang how process is created?

The process is created by calling spawn, and spawn forms a new process and returns the pid. spawn(Module, Name, Args) -> pid() Where - Module = Name = atom() Args = [Arg1,...,ArgN] ArgI = term()

What is Erlang processes?

Erlang is designed for massive concurrency. Erlang processes are lightweight (grow and shrink dynamically) with small memory footprint, fast to create and terminate, and the scheduling overhead is low.

How to include a file in Erlang what is the command used?

In two ways, a file can be included in Erlang-

  • include (File).
  • include_lib (File).

Explain what is PID datatype in Erlang?

PID mean Process Identifier and is the datatype used for the unique process identifiers which are assigned to every process. Processes communicate by sending and receiving messages through PID. Messages are sent by using the send operator ! and received by calling receive.

Explain what is Bit strings in Erlang?

A pattern matching occurs when evaluating a function call. Through pattern matching mechanism, variables are bound to the values. In a pattern matching, a left-hand side pattern is matched against a right-hand side term. If the matching succeeds, any unbound variables in the pattern become bound. If the matching fails, a run-time error occurs.

What is Bit strings in Erlang?

To store an area of untyped memory, a bit string is used and are expressed using the bit syntax.

how module is stored in Erlang?

A module name is stored in a file named .erl. File basename and module name must be the same.

Explain what is modules in Erlang?

Erlang enables to organize code into modules. A module consists of functions; it introduces a local scope of functions (Public and Private).

What is the command to disconnect node in Erlang?

By calling erlang: disconnect_node (Node) will force disconnection of the node.

Name the datatypes that erlang provides?

Erlang provides two datatypes

  • Constant data types: These types of data types cannot be split into more primitive subtypes. It consists of Numbers and Atoms.
  • Compound data types: These types of data types are used to group together other types of data types. It consists of tuples and lists.

What are the key features of Erlang?

Key features for Erlang is that it has

  • Declarative Syntax: It has got declarative syntax
  • Concurrent: It has process based model of concurrency
  • Real time: It programs real time system
  • Continuous Operation: It allows continuous operation
  • Robust: For detecting runtime errors it has three constructs in the language
  • Memory Management: Memory is allocated automatically and de-allocated when not required
  • Distribution: It has got no shared memory, distributed systems can be easily be built in erlang
  • Integration: Easy integration of program written in other language

What is erlang? Why it is best programming language for distributed applications?

Explain what is OTP (Open Telecom Platform)?

OTP is a collection of useful middleware, libraries, and tools written in the Erlang programming language. It is an integral part of the open-source distribution of Erlang. The name OTP was originally an acronym for Open Telecom Platform, which was a branding attempt before Ericsson released Erlang/OTP as opensource.

What is Erlang?

Erlang is a general purpose programming language and a runtime environment. It has built in support for concurrency, fault tolerance and distribution. Erlang is available as an open source.Erlang was originally developed to be used in several large telecommunication systems.

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