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Ur (programming Language)
Ur also called Ur/Web is a free and open-source functional programming language specific for web development, created by Adam Chlipala at the Massachusetts Institute of Technology that from a single program produces server code, browser client code and SQL code specific for the chosen database backend. Ur supports a powerful kind of metaprogramming based on row types. Ur/Web is Ur plus a special standard library and associated rules for parsing and optimization. Ur/Web supports construction of dynamic web applications backed by SQL databases. The signature of the standard library is such that well-typed Ur/Web programs "don't go wrong" in a very broad sense. Not only do they not crash during particular page generations, but they also may not: * Suffer from any kinds of code injection attacks * Return invalid HTML * Contain dead intra-application links * Have mismatches between HTML forms and the fields expected by their handlers * Include client-side code that makes incorrec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ML (programming Language)
ML (Meta Language) is a general-purpose functional programming language. It is known for its use of the polymorphic Hindley–Milner type system, which automatically assigns the types of most expressions without requiring explicit type annotations, and ensures type safetythere is a formal proof that a well-typed ML program does not cause runtime type errors. ML provides pattern matching for function arguments, garbage collection, imperative programming, call-by-value and currying. It is used heavily in programming language research and is one of the few languages to be completely specified and verified using formal semantics. Its types and pattern matching make it well-suited and commonly used to operate on other formal languages, such as in compiler writing, automated theorem proving, and formal verification. Overview Features of ML include a call-by-value evaluation strategy, first-class functions, automatic memory management through garbage collection, parametric polymorph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Web Page
A server-side dynamic web page is a web page whose construction is controlled by an application server processing server-side scripts. In server-side scripting, parameters determine how the assembly of every new web page proceeds, and including the setting up of more client-side processing. A client-side dynamic web page processes the web page using JavaScript running in the browser as it loads. JavaScript can interact with the page via Document Object Model, or DOM, to query page state and modify it. Even though a web page can be dynamic on the client-side, it can still be hosted on a static hosting service such as GitHub Pages or Amazon S3 as long as there isn't any server-side code included. A dynamic web page is then reloaded by the user or by a computer program to change some variable content. The updating information could come from the server, or from changes made to that page's DOM. This may or may not truncate the browsing history or create a saved version to go back ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Gateway Interface
In computing, Common Gateway Interface (CGI) is an interface specification that enables web servers to execute an external program, typically to process user requests. Such programs are often written in a scripting language and are commonly referred to as ''CGI scripts'', but they may include compiled programs. A typical use case occurs when a web user submits a web form on a web page that uses CGI. The form's data is sent to the web server within an HTTP request with a URL denoting a CGI script. The web server then launches the CGI script in a new computer process, passing the form data to it. The output of the CGI script, usually in the form of HTML, is returned by the script to the Web server, and the server relays it back to the browser as its response to the browser's request. Developed in the early 1990s, CGI was the earliest common method available that allowed a web page to be interactive. History In 1993, the National Center for Supercomputing Applications (NCSA) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monad (functional Programming)
In functional programming, a monad is a software design pattern with a structure that combines program fragments (Function (computer programming), functions) and wraps their return values in a Type system, type with additional computation. In addition to defining a wrapping monadic type, monads define two Operator (computer programming), operators: one to wrap a value in the monad type, and another to compose together functions that output values of the monad type (these are known as monadic functions). General-purpose languages use monads to reduce boilerplate code needed for common operations (such as dealing with undefined values or fallible functions, or encapsulating bookkeeping code). Functional languages use monads to turn complicated sequences of functions into succinct pipelines that abstract away control flow, and side-effect (computer science), side-effects. Both the concept of a monad and the term originally come from category theory, where a monad is defined as a Func ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard ML
Standard ML (SML) is a general-purpose, modular, functional programming language with compile-time type checking and type inference. It is popular among compiler writers and programming language researchers, as well as in the development of theorem provers. Standard ML is a modern dialect of ML, the language used in the Logic for Computable Functions (LCF) theorem-proving project. It is distinctive among widely used languages in that it has a formal specification, given as typing rules and operational semantics in ''The Definition of Standard ML''. Language Standard ML is a functional programming language with some impure features. Programs written in Standard ML consist of expressions as opposed to statements or commands, although some expressions of type unit are only evaluated for their side-effects. Functions Like all functional languages, a key feature of Standard ML is the function, which is used for abstraction. The factorial function can be expressed as follows: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garbage Collection (computer Science)
In computer science, garbage collection (GC) is a form of automatic memory management. The ''garbage collector'' attempts to reclaim memory which was allocated by the program, but is no longer referenced; such memory is called '' garbage''. Garbage collection was invented by American computer scientist John McCarthy around 1959 to simplify manual memory management in Lisp. Garbage collection relieves the programmer from doing manual memory management, where the programmer specifies what objects to de-allocate and return to the memory system and when to do so. Other, similar techniques include stack allocation, region inference, and memory ownership, and combinations thereof. Garbage collection may take a significant proportion of a program's total processing time, and affect performance as a result. Resources other than memory, such as network sockets, database handles, windows, file descriptors, and device descriptors, are not typically handled by garbage collection, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Type Safety
In computer science, type safety and type soundness are the extent to which a programming language discourages or prevents type errors. Type safety is sometimes alternatively considered to be a property of facilities of a computer language; that is, some facilities are type-safe and their usage will not result in type errors, while other facilities in the same language may be type-unsafe and a program using them may encounter type errors. The behaviors classified as type errors by a given programming language are usually those that result from attempts to perform operations on values that are not of the appropriate data type, e.g., adding a string to an integer when there's no definition on how to handle this case. This classification is partly based on opinion. Type enforcement can be static, catching potential errors at compile time, or dynamic, associating type information with values at run-time and consulting them as needed to detect imminent errors, or a combination of both. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Servers
A web server is computer software and underlying hardware that accepts requests via HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message. A web server can also accept and store resources sent from the user agent if configured to do so. The hardware used to run a web server can vary according to the volume of requests that it needs to handle. At the low end of the range are embedded systems, such as a router that runs a small web server as its configuration interface. A high-traffic Internet website might handle requests with hundreds of servers that run on racks of high-speed computers. A resource sent from a web server can be a preexisting file (static content) available to the web server, or it can be generated a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Browser
A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used on a range of devices, including desktops, laptops, tablets, and smartphones. In 2020, an estimated 4.9 billion people used a browser. The most used browser is Google Chrome, with a 65% global market share on all devices, followed by Safari with 18%. A web browser is not the same thing as a search engine, though the two are often confused. A search engine is a website that provides links to other websites. However, to connect to a website's server and display its web pages, a user must have a web browser installed. In some technical contexts, browsers are referred to as user agents. Function The purpose of a web browser is to fetch content from the World Wide Web or from local storage and display it on a user's device. This process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marshalling (computer Science)
In computer science, marshalling or marshaling ( US spelling) is the process of transforming the memory representation of an object into a data format suitable for storage or transmission. It is typically used when data must be moved between different parts of a computer program or from one program to another. Marshalling can be somewhat similar or synonymous to serialization. Marshalling is describing an intent or process to transfer some object from a client to server, intent is to have the same object that is present in one running program, to be present in another running program, i.e. object on a client to be transferred to and present on the server. Serialization does not necessarily have this intent since it is only concerned about transforming data into a, for example, stream of bytes. One could say that marshalling might be done in some other way from serialization, but some form of serialization is usually used. It simplifies complex communications, because it uses '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ajax (programming)
Ajax (also AJAX ; short for " Asynchronous JavaScript and XML") is a set of web development techniques that uses various web technologies on the client-side to create asynchronous web applications. With Ajax, web applications can send and retrieve data from a server asynchronously (in the background) without interfering with the display and behaviour of the existing page. By decoupling the data interchange layer from the presentation layer, Ajax allows web pages and, by extension, web applications, to change content dynamically without the need to reload the entire page. In practice, modern implementations commonly utilize JSON instead of XML. Ajax is not a technology, but rather a programming concept. HTML and CSS can be used in combination to mark up and style information. The webpage can be modified by JavaScript to dynamically display—and allow the user to interact with the new information. The built-in XMLHttpRequest object is used to execute Ajax on webpages, allowing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
