E is a concurrent, class-based, object-oriented programming language with a focus on security and reliable distributed systems. It was designed and developed by Mark S. Miller, Dan Ingalls, Bob Harper, and David Ungar at Xerox PARC in the mid-1980s. E has been used in a number of commercial and open-source projects, most notably the Inferno operating system.
E is based on the programming language Smalltalk-80. However, unlike Smalltalk, which is designed for educational and research purposes, E is intended for use in commercial software development. E is a direct descendant of the T programming language, which was developed at Xerox PARC in the early 1980s.
E is a concurrent programming language, which means that it is designed to support programs that can run in parallel. This is in contrast to most other programming languages, which are designed for programs that run sequentially.
E is a class-based language, which means that it uses a class hierarchy to define the relationships between objects. E also supports multiple inheritance, which means that a class can inherit from more than one other class.
E is an object-oriented language, which means that it uses objects to represent data and procedures. Objects can be created, destroyed, and passed as arguments to procedures. Object-oriented programming languages are designed to support the development of large, complex software systems.
E is a security-focused language. It includes features that are intended to make it difficult for programs to violate security policies. For example, E supports capability-based security, which means that an object can only be accessed if the program has the appropriate permissions.
E is a distributed programming language. It includes features that are intended to make it easy to develop programs that run on multiple computers. For example, E supports remote procedure calls, which means that a procedure can be invoked on a remote computer.
E is an open-source language. The reference implementation of the E programming language is available under an open-source license.
E is a general-purpose programming language. It can be used to develop a wide variety of applications.