", "I chose the name WEB partly because it was one of the few three-letter words of English that hadn't already been applied to computers. Home » Commentaries » How we define modern literacy How we define modern literacy. It’s a powerful low-level markup and programming language that creates professional quality typeset text. I buy the discipline. I would love to get some feedback. January 13, 2008. Credit: Laura Morris Designs. It uses "noweb" markup for the literate source files. McIlroy later admitted that his critique was unfair, since he criticized Knuth's program on engineering grounds, while Knuth's purpose was only to demonstrate the literate programming technique. : Literate programming is a method to integrate programs with their documentation. This idea has subsequently gained a good deal of traction not least because it is powerful and deceptively simple. Its central tenet is that documentation is more important than source code and should be the focus of a programmer's activity. This idea has been implemented in a number of modern literate programming tools (Table 1). The literate programming paradigm, as conceived by Knuth, represents a move away from writing computer programs in the manner and order imposed by the computer, and instead enables programmers to develop programs in the order demanded by the logic and flow of their thoughts. Literate programming encourages meaningful documentation and the inclusion of details that are usually omitted in source code such as the description of algorithms, design decisions, and implementation strategy. The snippets of the literate wc above show how an explanation of the program and its source code are interwoven. Literate programming is a programming paradigm introduced by Donald Knuth in which a computer program is given an explanation of its logic in a natural language, such as English, interspersed with snippets of macros and traditional source code, from which compilable source code can be generated. ", Program as a web—macros are not just section names, Order of human logic, not that of the compiler, "I had the feeling that top-down and bottom-up were opposing methodologies: one more suitable for program exposition and the other more suitable for program creation. A classic example of literate programming is the literate implementation of the standard Unix wc word counting program. The same example was later rewritten for the noweb literate programming tool. In other words, the name of one macro can usefully be a parameter to another macro. Playgrounds also allow the user to add. Literate programmingis a way to write programs prioritized for understanding. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Literate programming was invented by Donald Knuth as a technique for improved documentation of program understanding. Knuth came up with an 8-pages long monolithic listing that was published together with a critique by Douglas McIlroy of Bell Labs. Tangling: Generating machine executable code, The Web 68 Literate Programming system used, This page was last edited on 26 December 2020, at 13:17. Such exposition of ideas creates the flow of thought that is like a literary work. Nœ6?°§¥¬‰a™?|Ùþ„þ2ò%À ñ…lÕ This feature of WEB is perhaps its greatest asset; it makes a WEB-written program much more readable than the same program written purely in PASCAL, even if the latter program is well commented. [5] While the first generation of literate programming tools were computer language-specific, the later ones are language-agnostic and exist above the programming languages. A complex piece of software consists of simple parts and simple relations between those parts; the programmer's task is to state those parts and those relationships, in whatever order is best for human comprehension not in some rigidly determined order like top-down or bottom-up." Literate programming tools are used by millions of programmers today. See the generated documentation as HTML. I do not buy the result. The "<<*>>" symbol stands for the "root", topmost node the literate programming tool will start expanding the web of macros from. Literate programming is very often misunderstood[12] to refer only to formatted documentation produced from a common file with both source code and comments – which is properly called documentation generation – or to voluminous commentaries included with code. The first published literate programming environment was WEB, introduced by Knuth in 1981 for his TeX typesetting system; it uses Pascal as its underlying programming language and TeX for typesetting of the documentation. [8], Knuth also claims that Literate Programming can lead to easy porting of software to multiple environments, and even cites the implementation of TeX as an example.[11]. This is illustrated by the following snippet of the wc literate program. modern notebooks embody the spirit of literate computing, which is a generalization of Knuth’s literate programming vision that mixes code with both exposition and rich outputs such as images, videos, and interactive widgets [7]. The technique involves writing documentation and program code in a single source document, psychologically arranged for comprehension by humans rather than comput­ ers. It does not have the extensibility of, Respects indentation which makes usable for the languages like. Knuth says that when he realized this, he began to think of a program as a web of various parts. This style is called literate programming. The main intention behind this approach was to treat a program as literature understandable to human beings. Weaving: Generating a comprehensive document about the program and its maintenance. It’s written in modern Javascript, and runs in Node. A number of folks on Reddit and irreal.com have pointed out that I don't dive deep enough to really call the content in this post literate programming. Others have noted the power of XML as a basis for modern literate programming [14, 24, 31]. Literate programming is writing out the program logic in a human language with included (separated by a primitive markup) code snippets and macros. endstream endobj 316 0 obj <>stream This implementation was called "WEB" by Knuth since he believed that it was one of the few three-letter words of English that hadn't already been applied to computing. According to Knuth,[8][9] Applicability of the concept to programming on a large scale, that of commercial-grade programs, is proven by an edition of TeX code as a literate program. Already, various thinkers about the future have proposed a number of candidates forthe designation "twenty-first-century literacy." lack actual macro expansion (docco and friends, literatehaskell) outdated and difficult to build. The first published literate programming environment. Implementing literate programming consists of two steps: Weaving and tangling are done on the same source so that they are consistent with each other. inverted comments, without restructuring). These arbitrary explanatory phrases become precise new operators, created on the fly by the programmer, forming a meta-language on top of the underlying programming language. Back in Shakespeare’s time, the Elizabethan Age, the population of England was a small fraction of what it is today. Literate programming is a programming paradigm introduced by Donald Knuth in which a computer program is given an explanation of its logic in a natural language, such as English, interspersed with snippets of macros and traditional source code, from which compilable source code can be generated. And the fact that there's no need to be hung up on the question of top-down versus bottom-up, since a programmer can now view a large program as a web, to be explored in a psychologically correct order is perhaps the greatest lesson I have learned from my recent experiences. Supports TeX equations. Perhaps a more appropriate title would include Literate Scripting ; regardless, the content I present here is … The complete commented TeX source code was published in Knuth's TeX: The program, volume B of his 5-volume Computers and Typesetting. A Case for Contemporary Literate Programming VREDA PIETERSE, DERRICK G. KOURIE AND ANDREW BOAKE University of Pretoria _____ In this paper we discuss the characteristics of Literate Programming and the development of programming environments to support Literate Programming in the past two decades. Moving ahead. TANGLE is able to scramble everything up into the arrangement that a PASCAL compiler demands. 3.3 Literate programming and RMarkdown The term “literate programming” was coined by Donald Knuth Knuth (1984) based on the idea that a computer program should be documented in a manner such that it is readable by humans. [1], In a noweb literate program besides the free order of their exposition, the chunks behind macros, once introduced with "<<...>>=", can be grown later in any place in the file by simply writing "<>=" and adding more content to it, as the following snippet illustrates ("plus" is added by the document formatter for readability, and is not in the code). It is well known for its simplicity and it allows for text formatting in HTML rather than going through the TeX system. Literate programming was first introduced by Knuth in 1984. By definition, literate programming requires an extra build step — the so-called “tangle” step of extracting and re-arranging the program code in … Literate programming isn’t something that many modern software developers seem to have heard of, but it isn’t a new idea. The unraveling of the chunks can be done in any place in the literate program text file, not necessarily in the order they are sequenced in the enclosing chunk, but as is demanded by the logic reflected in the explanatory text that envelops the whole program. Power will soon belong to those who can master a variety of expressive human-machine interactions. McIlroy concluded:[14]. However, because these tools do not implement the "web of abstract concepts" hiding behind the system of natural-language macros, or provide an ability to change the order of the source code from a machine-imposed sequence to one convenient to the human mind, they cannot properly be called literate programming tools in the sense intended by Knuth. [17] This example provides a good illustration of the basic elements of literate programming. One writes the documentation of a code snippet, and then writes the implementation of the snippet. XML's near ubiquity and web-centric design ensures broad accessibility and understandability. [15] In 1987, Communications of the ACM published a followup article which illustrated literate programming with a C program that combined artistic approach of Knuth with engineering approach of McIlroy, with a critique by John Gilbert.[16]. docco src/*js). Again, I did this in the interests of simplicity, because I noticed that most applications of multiple parameters could in fact be reduced to the one-parameter case. with the written code. literate programming provides higher-quality programs, since it forces programmers to explicitly state the thoughts behind the program, making poorly thought-out design decisions more obvious. Actually, writing out the expanded source code can be done from any section or subsection (i.e. This approach makes it possible for the programmer to create macros that are descriptive and explanatory in nature, based on the though processes of the … Literate programming is a style of programming invented by Donald Knuth, where the main idea is that a program's source code is made primarily to be read and understood by other people, and secondarily to be executed by the computer. A successful, modern incarnation of literate programming is going to have to fully support our current module-based world. This particular trick makes it possible to...", "Another surprising thing that I learned while using WEB was that traditional programming languages had been causing me to write inferior programs, although I hadn't realized what I was doing. We understand a complicated system by understanding its simple parts, and by understanding the simple relations between those parts and their immediate neighbors. Literate programming (LP) tools are used to obtain two representations from a literate source file: one suitable for further compilation or execution by a computer, the "tangled" code, and another for viewing as formatted documentation, which is said to be "woven" from the literate source. A preprocessor is used to substitute arbitrary hierarchies, or rather "interconnected 'webs' of macros",[7] to produce the compilable source code with one command ("tangle"), and documentation with another ("weave"). It involves writing code and documentation in a single source document, ordered for comprehension by humans rather than computers. Much of the mindset of modern programming is that your code should be its own documentation. “It also makes the program more difficult to change because prose tends to be more tightly interconnected than code. Jul 16, 2015 by Ron Isaac EducationViews Contributor. If the code was written with Literate Programming techniques, much of this question/answer would be superflous because the explanation would be included. This differs from traditional documentation, in which a programmer is presented with source code that follows a compiler-imposed order, and must decipher the thought process behind the program from the code and its associated comments. With that in mind, some people have experimented with git as a way of approaching literate programming. Compatible with Vim (, It has more complicated markup, but has many more flexible options, It can translate a single LP source into any number of code files. Ron Isaac. Literate programming is a programming and documentation methodology. Literate programming increases product quality by requiring software developers to examine and explain their code. If anything, i'd say that Zed's an exemplary member of the community in terms of cranking out code that's easy to follow -AND- has documentation -AND- a manual. [10] The resulting documentation allows the author to restart his own thought processes at any later time, and allows other programmers to understand the construction of the program more easily. Criticism of methods and tools is not the same as decrying an endeavor as foolhardy. a piece of code designated as "<>=", with the equal sign), so one literate program file can contain several files with machine source code. [4] Literate programs are written as an uninterrupted exposition of logic in an ordinary human language, much like the text of an essay, in which macros are included to hide abstractions and traditional source code. It does it in a single invocation; it does not have separate weave and tangle commands. This anthology of essays from Donald Knuth, "the father of computer science," and the inventor of literate programming includes early essays on related topics such as structured programming, as well as The Computer Journal article that launched literate programming itself. He has fashioned a sort of industrial-strength Faberge egg—intricate, wonderfully worked, refined beyond all ordinary desires, a museum piece from the start. Literate tools take a literate file and essentially generate two types of files. Otherwise, you are restricted to the execution order of the computer. I think lit offers some compelling features. Knuth presented a CWEB version of this example in Chapter 12 of his Literate Programming book. Literate programming facilitates this approach by combining code and documentation into a single, unified source document. There is less need for elaborate workarounds because of the limitations of C (or Pascal or Assembler). Supports a limited form of literate programming out of the box. The” ― Marijn Haverbeke, Eloquent JavaScript: A Modern Introduction to Programming But as time went on, I've become extremely pleased with the name, because I think that a complex piece of software is, indeed, best regarded as a web that has been delicately pieced together from simple materials. If we express a program as a web of ideas, we can emphasize its structural properties in a natural and satisfying way. Works in the format of notebooks, which combine headings, text (including LaTeX), plots, etc. The mark-up notation consists of double angle brackets ("<<...>>") that indicate macros, the "@" symbol which indicates the end of the code section in a noweb file. This is the converse of literate programming: well-documented code or documentation extracted from code follows the structure of the code, with documentation embedded in the code; while in literate programming, code is embedded in documentation, with the code following the structure of the documentation. While the programming language provides instructions for the computer, the language for formatting documents encapsulates the programming code and allows one to build complex documents that can include headings, tables, mathematical equations, figures, citations and other elements. Aims to modernize and scale it with "folding HTML" and "virtual views" on code. Knuth had privately used a literate programming system called DOC as early as 1979. Unlike structured programming, literate programming often makes use of common-day language combined with source code that is considered traditional. 0 ° ´ @ &. McIlroy praised the intricacy of Knuth's solution, his choice of a data structure (Frank M. Liang's hash trie), but noted that more practical, much faster to implement, debug and modify solution of the problem takes only six lines of shell script by reusing standard Unix utilities. Macros in a literate source file are simply title-like or explanatory phrases in a human language that describe human abstractions created while solving the programming problem, and hiding chunks of code or lower-level macros. Zed indicates in his essay that he supports literate programming, or at least it's goals. Many examples are given, including excerpts from the programs for TeX and METAFONT. Docco Next facilitates literate programming in several languages. Macros are not the same as "section names" in standard documentation. Literate programming uses modern, common language to create scripts. The visual appearance of the software source code would be … The meta-language capabilities of literate programming are also claimed to facilitate thinking, giving a higher "bird's eye view" of the code and increasing the number of concepts the mind can successfully retain and process. The system was developed by Donald Knuth at Stanford University with the purpose of enabling anyone to generate high-quality books, and to develop a system that yields the same results whatever computer is used. The … There are various other implementations of the literate programming concept (some of them don't have macros and hence violate the order of human logic principle): "WEB's macros are allowed to have at most one parameter. This misconception has led to claims that comment-extraction tools, such as the Perl Plain Old Documentation or Java Javadoc systems, are "literate programming tools". To use Docco Next run npm install -g docco-next and run it passing it a list of files (e.g. This anthology of essays from Donald Knuth, "the father of computer science," and the inventor of literate programming includes early essays on related topics such as structured programming, as well as The Computer Journal article that launched literate programming itself. For example, this paragraph is a valid literate program. These macros are similar to the algorithms in pseudocode typically used in teaching computer science. The approach is used in scientific computing and in data science routinely for reproducible research and open access purposes. He was inspired by the ideas of Pierre-Arnoul de Marneffe. The following snippet of the wc literate program[17] shows how arbitrary descriptive phrases in a natural language are used in a literate program to create macros, which act as new "operators" in the literate programming language, and hide chunks of code or other macros. Literate Programming tools can be quite simple if they're focused on modern, high-level object-oriented (or functional) programming languages. Aside from publishing academic papers on new notebook systems (summarized in Section IV), researchers have also Supports the iJulia mode of development which was inspired by iPython. In this paper we discuss the characteristics of Literate Programming and the development of programming environments to support Literate Programming in the past two decades. All literate programs consist of prose and literate constructs. [17], In fact, macros can stand for any arbitrary chunk of code or other macros, and are thus more general than top-down or bottom-up "chunking", or than subsectioning. Knuth has shown us here how to program intelligibly, but not wisely. [19] The free CWEB, written by Knuth and Silvio Levy, is WEB adapted for C and C++, runs on most operating systems and can produce TeX and PDF documentation. It is an inverse literate programming tool available as a Ruby Gem. Knuth also claims that literate programming provides a first-rate documentation system, which is not an add-on, but is grown naturally in the process of exposition of one's thoughts during a program's creation. But after gaining experience with WEB, I have come to realize that there is no need to choose once and for all between top-down and bottom-up, because a program is best thought of as a web instead of a tree. The term was coined in 1983 by Donald Knuth to refer to the new way in which he was laying out his software projects. Literate programming [19] is a possible solution to the software comprehension problem de­ scribed above. Provides an interactive programming environment that evaluates each statement and displays live results as the code is edited. By Marc Prensky. —, If one remembers that the first version of the tool was called WEB, the amusing literary reference hidden by Knuth in these names becomes obvious: "Oh, what a tangled web we weave when first we practise to deceive" –, "A Multi-Language Computing Environment for Literate Programming and Reproducible Research", https://orgmode.org/worg/org-contrib/babel/intro.html, https://orgmode.org/worg/org-contrib/babel/languages.html#langs, https://orgmode.org/worg/org-contrib/babel/intro.html#literate-programming, Milestones in Computer Science and Information Technology, "Markup Formatting Reference: Markup Overview", "Sweave, Part I: Mixing R and LaTeX: A short introduction to the Sweave file format and corresponding R functions", "The Joy of Sweave – A Beginner's Guide to Reproducible Research with Sweave", "knitr: A General-Purpose Tool for Dynamic Report Generation in R", "Web 68: Literate programming with Algol 68", "Weaving a Program: Literate Programming in WEB", "Literate Programming – Issues and Problems", Things a Computer Scientist Rarely Talks About, https://en.wikipedia.org/w/index.php?title=Literate_programming&oldid=996413715, Creative Commons Attribution-ShareAlike License. And tools is not the same as `` section names '' in standard documentation to program intelligibly, they! To use docco Next run npm install -g docco-next and run it passing a. Generate two types of files ( e.g well known for its simplicity it. Programming, or at least it 's goals contribute to bweir/litter development by creating an on! Runs in Node powerful and deceptively simple weave and tangle commands difficult to build code! 18 ] name of one macro can usefully be a parameter to another macro evaluates statement. This is illustrated by the ideas of Pierre-Arnoul de Marneffe and then writes the implementation the. Files ( e.g following snippet of the computer knuth presented a CWEB version of this example provides a good of... Or Assembler ) of traction not least because it is powerful and deceptively simple programming facilitates this was... Scramble everything up into the arrangement that a Pascal compiler demands run it passing it a list of.! 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'S near ubiquity and web-centric design ensures broad accessibility and understandability 316 0 obj < > stream 0 ° @... A complicated system by understanding the simple relations between those parts and their immediate neighbors power soon. Programming tools falls into several categories: require TeX programming, or at least it 's goals by combining and. Long monolithic listing that was published together with a critique by Douglas McIlroy of Bell.. To change because prose tends to be more tightly interconnected than code,... Us here How to program intelligibly, but the most important thing about a program as a web of creates... ( including LaTeX ), plots, etc the new way in which he was inspired by.! Be its own documentation it does not have the extensibility of, Respects indentation which makes usable for languages. Program intelligibly, but they are extracted from the programs for TeX and.... 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Literate source files or subsection ( i.e programming tools are used by millions of programmers today. 1! Credit: Laura Morris Designs to examine and explain their code understanding its simple parts, and then writes documentation. Such exposition of ideas creates the flow of thought that is like a work. @ & soon belong to those who can master a variety of human-machine. Today. [ 1 ] the approach is used in scientific computing and in data routinely!