Read–eval–print Loop
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Read–eval–print Loop
A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple interactive computer programming environment that takes single user inputs, executes them, and returns the result to the user; a program written in a REPL environment is executed piecewise. The term usually refers to programming interfaces similar to the classic Lisp machine interactive environment. Common examples include command-line shells and similar environments for programming languages, and the technique is very characteristic of scripting languages. History The first Read-Eval-Print loop, ''cycle'', was invented in 1964 by L. Peter Deutsch and Edmund Berkeley for an implementation of Lisp on the PDP-1. Overview In a REPL, the user enters one or more expressions (rather than an entire compilation unit) and the REPL evaluates them and displays the results. The name ''read–eval–print loop'' comes from the names of the Lisp primitive functions which implement this fu ...
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Computer Programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms (usually in a chosen programming language, commonly referred to as coding). The source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, which is directly executed by the central processing unit. The purpose of programming is to find a sequence of instructions that will automate the performance of a task (which can be as complex as an operating system) on a computer, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algori ...
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CLIM
The Common Lisp Interface Manager (CLIM) is a Common Lisp-based programming interface for creating user interfaces, i.e., graphical user interfaces (GUIs). It provides an application programming interface (API) to user interface facilities for the programming language Lisp. It is a fully object-oriented programming user interface management system, using the Common Lisp Object System (CLOS) and is based on the mechanism of stream input and output. There are also facilities for output device independence. It is descended from the GUI system Dynamic Windows of Symbolics' Lisp machines between 1988 and 1993. The main development was CLIM 2.0, released in 1993. It is free and open source software released under a GNU Library General Public License (LGPL). CLIM has been designed to be portable across different Common Lisp implementations and different windowing systems. It uses a reflective architecture for its window system interface. CLIM supports, like Dynamic Windows, so-called Pr ...
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Direct Mode
In computing, direct or immediate mode in an interactive programming system is the immediate execution of commands, statements, or expressions. In many interactive systems, most of these can both be included in programs or executed directly in a read–eval–print loop (REPL). Most interactive systems also offer the possibility of defining programs in the REPL, either with explicit declarations, such as Python's def, or by labelling them with line numbers. Programs can then be run by calling a named or numbered procedure or by running a main program. Many programming systems, from Lisp and JOSS to Python and Perl have interactive REPLs which also allow defining programs. Most integrated development environment An integrated development environment (IDE) is a software application that provides comprehensive facilities to computer programmers for software development. An IDE normally consists of at least a source code editor, build automation tools ...s offer a direct ...
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Variable (programming)
In computer programming, a variable is an abstract storage location paired with an associated symbolic name, which contains some known or unknown quantity of information referred to as a ''value''; or in simpler terms, a variable is a named container for a particular set of bits or type of data (like integer, float, string etc...). A variable can eventually be associated with or identified by a memory address. The variable name is the usual way to reference the stored value, in addition to referring to the variable itself, depending on the context. This separation of name and content allows the name to be used independently of the exact information it represents. The identifier in computer source code can be bound to a value during run time, and the value of the variable may thus change during the course of program execution. Variables in programming may not directly correspond to the concept of variables in mathematics. The latter is abstract, having no reference to a physi ...
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Mouse (computing)
A computer mouse (plural mice, sometimes mouses) is a hand-held pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface of a computer. The first public demonstration of a mouse controlling a computer system was in 1968. Mice originally used two separate wheels to track movement across a surface: one in the X-dimension and one in the Y. Later, the standard design shifted to utilize a ball rolling on a surface to detect motion. Most modern mice use optical sensors that have no moving parts. Though originally all mice were connected to a computer by a cable, many modern mice are cordless, relying on short-range radio communication with the connected system. In addition to moving a cursor, computer mice have one or more buttons to allow operations such as the selection of a menu item on a display. Mice often also feature ...
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Error Handling
In computing and computer programming, exception handling is the process of responding to the occurrence of ''exceptions'' – anomalous or exceptional conditions requiring special processing – during the execution of a program. In general, an exception breaks the normal flow of execution and executes a pre-registered ''exception handler''; the details of how this is done depend on whether it is a hardware or software exception and how the software exception is implemented. Exception handling, if provided, is facilitated by specialized programming language constructs, hardware mechanisms like interrupts, or operating system (OS) inter-process communication (IPC) facilities like signals. Some exceptions, especially hardware ones, may be handled so gracefully that execution can resume where it was interrupted. Definition The definition of an exception is based on the observation that each procedure has a precondition, a set of circumstances for which it will terminate "normall ...
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Benchmarking
Benchmarking is the practice of comparing business processes and performance metrics to industry bests and best practices from other companies. Dimensions typically measured are quality, time and cost. Benchmarking is used to measure performance using a specific indicator (cost per unit of measure, productivity per unit of measure, cycle time of x per unit of measure or defects per unit of measure) resulting in a metric of performance that is then compared to others. Also referred to as "best practice benchmarking" or "process benchmarking", this process is used in management in which organizations evaluate various aspects of their processes in relation to best-practice companies' processes, usually within a peer group defined for the purposes of comparison. This then allows organizations to develop plans on how to make improvements or adapt specific best practices, usually with the aim of increasing some aspect of performance. Benchmarking may be a one-off event, but is often ...
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IPython
IPython (Interactive Python) is a command shell for interactive computing in multiple programming languages, originally developed for the Python programming language, that offers introspection, rich media, shell syntax, tab completion, and history. IPython provides the following features: * Interactive shells (terminal and Qt-based). * A browser-based notebook interface with support for code, text, mathematical expressions, inline plots and other media. * Support for interactive data visualization and use of GUI toolkits. * Flexible, embeddable interpreters to load into one's own projects. * Tools for parallel computing. IPython is a NumFOCUS fiscally sponsored project. Parallel computing IPython is based on an architecture that provides parallel and distributed computing. IPython enables parallel applications to be developed, executed, debugged and monitored interactively, hence the I (Interactive) in IPython. This architecture abstracts out parallelism, enabling IPython ...
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Software Prototyping
Software prototyping is the activity of creating prototypes of software applications, i.e., incomplete versions of the software program being developed. It is an activity that can occur in software development and is comparable to prototyping as known from other fields, such as mechanical engineering or manufacturing. A prototype typically simulates only a few aspects of, and may be completely different from, the final product. Prototyping has several benefits: the software designer and implementer can get valuable feedback from the users early in the project. The client and the contractor can compare if the software made matches the software specification, according to which the software program is built. It also allows the software engineer some insight into the accuracy of initial project estimates and whether the deadlines and milestones proposed can be successfully met. The degree of completeness and the techniques used in prototyping have been in development and debate si ...
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JShell
JShell is a Java read-eval-print loop which was first introduced in the JDK 9. It is tracked by JEP 222 ''jshell: The Java Shell (Read-Eval-Print Loop)''. One reason why JShell was proposed for Java 9 is the lack of a standard interactive environment for the language; the ''de facto'' library to use a Java REPL was often BeanShell, which has been dormant since 2003, and arbitrarily diverged from the Java language. Example jshell> int a[] = a > int[5] jshell> int fact(int n) , created method fact(int) jshell> for (int i=0 ; i a[i] = fact(a[i]); jshell> a a > int[5] See also * Exploratory programming References Command shells Cross-platform software Virtual machine In computing, a virtual machine (VM) is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardw ... Java platform software Interpreters (computing ...
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Java (programming Language)
Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers ''write once, run anywhere'' ( WORA), meaning that compiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture. The syntax of Java is similar to C and C++, but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities (such as reflection and runtime code modification) that are typically not available in traditional compiled languages. , Java was one of the most popular programming languages in use according to GitHub, particularly for client–server web applications, with a reported 9 million developers. Java was originally developed ...
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Interpreter (computing)
In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An interpreter generally uses one of the following strategies for program execution: # Parse the source code and perform its behavior directly; # Translate source code into some efficient intermediate representation or object code and immediately execute that; # Explicitly execute stored precompiled bytecode made by a compiler and matched with the interpreter Virtual Machine. Early versions of Lisp programming language and minicomputer and microcomputer BASIC dialects would be examples of the first type. Perl, Raku, Python, MATLAB, and Ruby are examples of the second, while UCSD Pascal is an example of the third type. Source programs are compiled ahead of time and stored as machine independent code, which is then linked at run-time and executed by ...
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