Computing

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to very much further sort and understand.

General

A program is many things. It is a piece of text typed by a programmer, it is the directing force that makes the computer do what it does, it is data in the computer's memory, yet it controls the actions performed on this same memory. Analogies that try to compare programs to objects we are familiar with tend to fall short, but a superficially fitting one is that of a machine. The gears of a mechanical watch fit together ingeniously, and if the watchmaker was any good, it will accurately show the time for many years. The elements of a program fit together in a similar way, and if the programmer knows what he is doing, the program will run without crashing.
A computer is a machine built to act as a host for these immaterial machines. Computers themselves can only do stupidly straightforward things. The reason they are so useful is that they do these things at an incredibly high speed. A program can, by ingeniously combining many of these simple actions, do very complicated things. ... When a program works, it is beautiful. The art of programming is the skill of controlling complexity. The great program is subdued, made simple in its complexity.

-- http://eloquentjavascript.net/chapter1.html

Basics

Eric Steven Raymond;

  • Pipe Logic - "In this model, a UNIX pipe acts like a wire, that is, a conductor with parasitic capacitance."
  • Simple Made Easy - Rich Hickey emphasizes simplicity’s virtues over easiness’, showing that while many choose easiness they may end up with complexity, and the better way is to choose easiness along the simplicity path. ]

Reference

OS

  • OSDev.org - wiki that provides information about the creation of operating systems and serves as a community for those people interested in OS creation

Books

News and Blogs

People

Tools

Computation

See also Maths#Logic

  • https://en.wikipedia.org/wiki/Theory_of_computation - deals with how efficiently problems can be solved on a model of computation, using an algorithm. The field is divided into three major branches: automata theory, computability theory, and computational complexity theory.

People

Theory

to sort

  • https://en.wikipedia.org/wiki/Computability_theory - also called recursion theory, is a branch of mathematical logic, of computer science, and of the theory of computation that originated in the 1930s with the study of computable functions and Turing degrees.

The basic questions addressed by recursion theory are "What does it mean for a function on the natural numbers to be computable?" and "How can noncomputable functions be classified into a hierarchy based on their level of noncomputability?". The answers to these questions have led to a rich theory that is still being actively researched. The field has since grown to include the study of generalized computability and definability.

  • https://en.wikipedia.org/wiki/Computable_function - the basic objects of study in computability theory. Computable functions are the formalized analogue of the intuitive notion of algorithm. They are used to discuss computability without referring to any concrete model of computation such as Turing machines or register machines. Any definition, however, must make reference to some specific model of computation but all valid definitions yield the same class of functions. Particular models of computability that give rise to the set of computable functions are the Turing-computable functions and the μ-recursive functions.
  • https://en.wikipedia.org/wiki/Turing_degree - or degree of unsolvability of a set of natural numbers measures the level of algorithmic unsolvability of the set. The concept of Turing degree is fundamental in computability theory, where sets of natural numbers are often regarded as decision problems; the Turing degree of a set tells how difficult it is to solve the decision problem associated with the set. That is, to determine whether an arbitrary number is in the given set.


  • https://en.wikipedia.org/wiki/Recursive_set - a set of natural numbers is called recursive, computable or decidable if there is an algorithm which terminates after a finite amount of time and correctly decides whether or not a given number belongs to the set. A more general class of sets consists of the recursively enumerable sets, also called semidecidable sets. For these sets, it is only required that there is an algorithm that correctly decides when a number is in the set; the algorithm may give no answer (but not the wrong answer) for numbers not in the set. A set which is not computable is called noncomputable or undecidable.


  • https://en.wikipedia.org/wiki/Recursively_enumerable_set - a set S of natural numbers is called recursively enumerable, computably enumerable, semidecidable, provable or Turing-recognizable if: There is an algorithm such that the set of input numbers for which the algorithm halts is exactly S, or equivalently; There is an algorithm that enumerates the members of S. That means that its output is simply a list of the members of S: s1, s2, s3, ... . If necessary, this algorithm may run forever. The first condition suggests why the term semidecidable is sometimes used; the second suggests why computably enumerable is used. The abbreviations r.e. and c.e. are often used, even in print, instead of the full phrase. In computational complexity theory, the complexity class containing all recursively enumerable sets is RE.



  • https://en.wikipedia.org/wiki/Grzegorczyk_hierarchy - a hierarchy of functions used in computability theory (Wagner and Wechsung 1986:43). Every function in the Grzegorczyk hierarchy is a primitive recursive function, and every primitive recursive function appears in the hierarchy at some level. The hierarchy deals with the rate at which the values of the functions grow; intuitively, functions in lower level of the hierarchy grow slower than functions in the higher levels.


  • https://en.wikipedia.org/wiki/Curry–Howard_correspondence - the direct relationship between computer programs and mathematical proofs. It is a generalization of a syntactic analogy between systems of formal logic and computational calculi that was first discovered by the American mathematician Haskell Curry and logician William Alvin Howard.
  • The Holy Trinity - "The doctrine of computational trinitarianism holds that computation manifests itself in three forms: proofs of propositions, programs of a type, and mappings between structures. These three aspects give rise to three sects of worship: Logic, which gives primacy to proofs and propositions; Languages, which gives primacy to programs and types; Categories, which gives primacy to mappings and structures. The central dogma of computational trinitarianism holds that Logic, Languages, and Categories are but three manifestations of one divine notion of computation. There is no preferred route to enlightenment: each aspect provides insights that comprise the experience of computation in our lives."
  • Physics, Topology, Logic and Computation: A Rosetta Stone [1] - "In physics, Feynman diagrams are used to reason about quantum processes. In the 1980s, it became clear that underlying these diagrams is a powerful analogy between quantum physics and topology: namely, a linear operator behaves very much like a "cobordism". Similar diagrams can be used to reason about logic, where they represent proofs, and computation, where they represent programs. With the rise of interest in quantum cryptography and quantum computation, it became clear that there is extensive network of analogies between physics, topology, logic and computation. In this expository paper, we make some of these analogies precise using the concept of "closed symmetric monoidal category". We assume no prior knowledge of category theory, proof theory or computer science."



  • Where LISP Fits - [2] - "These simplifications made LISP into a way of describing computable functions much neater than the Turing machines or the general recursive definitions used in recursive function theory. The fact that Turing machines constitute an awkward programming language doesn’t much bother recursive function theorists, because they almost never have any reason to write particular recursive definitions, since the theory concerns recursive functions in general. They often have reason to prove that recursive functions with specific properties exist, but this can be done by an informal argument without having to write them down explicitly. In the early days of computing, some people developed programming languages based on Turing machines; perhaps it seemed more scientific. Anyway, I decided to write a paper describing LISP both as a programming language and as a formalism for doing recursive function theory."


Automata theory

  • https://en.wikipedia.org/wiki/Automata_theory - a mathematical object that takes a word as input and decides either to accept it or reject it. Since all computational problems are reducible into the accept/reject question on words (all problem instances can be represented in a finite length of symbols) automata theory plays a crucial role in computational theory.


Cellular automaton

Turing machine

Lambda calculus

Complexity



to sort






Processing






Syntax

Data types

  • https://en.wikipedia.org/wiki/Type_theory - any of a class of formal systems, some of which can serve as alternatives to set theory as a foundation for all mathematics. In type theory, every "term" has a "type" and operations are restricted to terms of a certain type.
  • https://en.wikipedia.org/wiki/Data_type
  • https://en.wikipedia.org/wiki/Type_system - a collection of rules that assign a property called a type to constructs such as variables, expressions, functions or modules—a computer program is composed of. reduces bugs by defining interfaces between different parts of a computer program, and then checking that the parts have been connected in a consistent way. This checking can happen statically (at compile time), dynamically (at run time), or as a combination thereof.
  • https://en.wikipedia.org/wiki/Duck_typing - style of typing in which an object's methods and properties determine the valid semantics, rather than its inheritance from a particular class or implementation of a specific interface
  • https://en.wikipedia.org/wiki/Substructural_type_system - family of type systems analogous to substructural logics where one or more of the structural rules are absent or allowed under controlled circumstances. Such systems are useful for constraining access to system resources such as files, locks and memory by keeping track of changes of state that occur and preventing invalid states

Numbers

Data structures

The difference between arrays and linked lists are:

- Arrays are linear data structures. Linked lists are linear and non-linear data structures. - Linked lists are linear for accessing, and non-linear for storing in memory - Array has homogenous values. And each element is independent of each other positions. Each node in the linked list is connected with its previous node which is a pointer to the node. - Array elements can be modified easily by identifying the index value. It is a complex process for modifying the node in a linked list. - Array elements can not be added, deleted once it is declared. The nodes in the linked list can be added and deleted from the list.

Mutability

Objects

Evaluation

An expression evaluates to a value. A statement does something. 

x = 1
y = x + 1     # an expression
print y       # a statement, prints 2

Operators

Control structures

Algorithms

See also Maths

  • https://en.wikipedia.org/wiki/Algorithmic_information_theory - a subfield of information theory and computer science that concerns itself with the relationship between computation and information. According to Gregory Chaitin, it is "the result of putting Shannon's information theory and Turing's computability theory into a cocktail shaker and shaking vigorously."

Functions

  • subroutine is a sequence of program instructions that perform a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed. Subprograms may be defined within programs, or separately in libraries that can be used by multiple programs. In different programming languages a subroutine may be called a procedure, a function, a routine, a method, or a subprogram. The generic term callable unit is sometimes used.

Paradigms

Patterns

MV*

"create your views, express your models or develop a controller"

Libraries

Module pattern

Functional

  • λ Lessons - Pattern matching, first-class functions, and abstracting over recursion in Haskell. This is a short, interactive lesson that teaches core functional programming concepts. It was designed to transform the way you think about performing operations on lists of things, by showing you how functions are executed. [30]

Memory

Garbage collection

Threads

Polymorphism

Macros

Compilation and interpretation

  • GNU Compiler Collection includes front ends for C, C++, Objective-C, Fortran, Java, Ada, and Go, as well as libraries for these languages (libstdc++, libgcj,...). GCC was originally written as the compiler for the GNU operating system. The GNU system was developed to be 100% free software, free in the sense that it respects the user's freedom.
  • LLVM is a collection of modular and reusable compiler and toolchain technologies. Despite its name, LLVM has little to do with traditional virtual machines, though it does provide helpful libraries that can be used to build them. The name "LLVM" itself is not an acronym; it is the full name of the project.
  • Emscripten is an LLVM to JavaScript compiler. It takes LLVM bitcode (which can be generated from C/C++ using Clang, or any other language that can be converted into LLVM bitcode) and compiles that into JavaScript, which can be run on the web (or anywhere else JavaScript can run).
  • Parrot is a virtual machine designed to efficiently compile and execute bytecode for dynamic languages. Parrot currently hosts a variety of language implementations in various stages of completion, including Tcl, Javascript, Ruby, Lua, Scheme, PHP, Python, Perl 6, APL, and a .NET bytecode translator. Parrot is not about parrots, though we are rather fond of them for obvious reasons.


  • XMLVM is to offer a flexible and extensible cross-compiler toolchain. Instead of cross-compiling on a source code level, XMLVM cross-compiles byte code instructions from Sun Microsystem's virtual machine and Microsoft's Common Language Runtime. The benefit of this approach is that byte code instructions are easier to cross-compile and the difficult parsing of a high-level programming language is left to a regular compiler. In XMLVM, byte code-based programs are represented as XML documents. This allows manipulation and translation of XMLVM-based programs using advanced XML technologies such as XSLT, XQuery, and XPath.


Metaprogramming

Monads

Aspect of functional. See Haskell, etc. for related.

Concurrency

Events

Messaging

  • ØMQ \zeromq\
    •  The socket library that acts as a concurrency framework.
    •   Faster than TCP, for clustered products and supercomputing.
<tef> but glyph is the serialization format really :-)
  • MessagePack is an efficient binary serialization format. It lets you exchange data among multiple languages like JSON but it's faster and smaller. For example, small integers (like flags or error code) are encoded into a single byte, and typical short strings only require an extra byte in addition to the strings themselves.

Futures and promises

Distributed

Command-line

GUI

NLP

Development

a mess

Engineering

See also Organisation#Collaboration



  • Formal Methods of Software Design - using mathematics to write error-free programs. The mathematics needed is not complicated; it's just boolean algebra. The word "formal" means the use of a formal language, so that the program logic can be machine checked. Our compilers already tell us if we make a syntax error, or a type error, and they tell us what and where the error is. Formal methods take the next step, telling us if we make a logic error, and they tell us what and where the error is. And they tell us this as we make the error, not after the program is finished. It is good to get any program correct while writing it, rather than waiting for bug reports from users. It is absolutely essential for programs that lives will depend on.


  1. Do you use source control?
  2. Can you make a build in one step?
  3. Do you make daily builds?
  4. Do you have a bug database?
  5. Do you fix bugs before writing new code?
  6. Do you have an up-to-date schedule?
  7. Do you have a spec?
  8. Do programmers have quiet working conditions?
  9. Do you use the best tools money can buy?
  10. Do you have testers?
  11. Do new candidates write code during their interview?
  12. Do you do hallway usability testing?

Versioning

Source control

  • Gource is a software version control visualization tool.

VCS

See Git

  • Gource is a software version control visualization tool.

Debugging

DTrace

Testing

  • Build it, test it, release it, monitor it
  • Google: single tree, development on head, parallel build and tests, cached
  • https://en.wikipedia.org/wiki/Test_strategy - an outline that describes the testing approach of the software development cycle. It is created to inform project managers, testers, and developers about some key issues of the testing process. This includes the testing objective, methods of testing new functions, total time and resources required for the project, and the testing environment.

Test strategies describe how the product risks of the stakeholders are mitigated at the test-level, which types of test are to be performed, and which entry and exit criteria apply. They are created based on development design documents. System design documents are primarily used and occasionally, conceptual design documents may be referred to. Design documents describe the functionality of the software to be enabled in the upcoming release. For every stage of development design, a corresponding test strategy should be created to test the new feature sets.

  • https://en.wikipedia.org/wiki/Test_plan - a document detailing a systematic approach to testing a system such as a machine or software. The plan typically contains a detailed understanding of the eventual workflow.
  • https://en.wikipedia.org/wiki/Black-box_testing - examines the functionality of an application (e.g. what the software does) without peering into its internal structures or workings. This method of test can be applied to virtually every level of software testing: unit, integration, system and acceptance. It typically comprises most if not all higher level testing, but can also dominate unit testing as well.
  • https://en.wikipedia.org/wiki/Static_testing - a form of software testing where the software isn't actually used. checks mainly for the sanity of the code, algorithm, or document. It is primarily checking of the code and/or manually reviewing the code or document to find errors. This type of testing can be used by the developer who wrote the code, in isolation. Code reviews, inspections and Software walkthroughs are also used.
  • https://en.wikipedia.org/wiki/Dynamic_testing - dynamic analysis refers to the examination of the physical response from the system to variables that are not constant and change with time. In dynamic testing the software must actually be compiled and run. It involves working with the software, giving input values and checking if the output is as expected by executing specific test cases which can be done manually or with the use of an automated process. This is in contrast to static testing. Unit tests, integration tests, system tests and acceptance tests utilize dynamic testing.

Unit testing

  • https://en.wikipedia.org/wiki/Test_suite - less commonly known as a validation suite, is a collection of test cases that are intended to be used to test a software program to show that it has some specified set of behaviours. A test suite often contains detailed instructions or goals for each collection of test cases and information on the system configuration to be used during testing. A group of test cases may also contain prerequisite states or steps, and descriptions of the following tests.

TDD

BDD

  • Behavior Driven Development - BDD evolved by incorporating what works from Test Driven Development, Agile User Stories, Domain Driven Design and XP with an emphasis on product behavior testing over unit testing. Project stakeholders and team members focus on the problem domain and develop a common language for expressing a product's desired behavior as stories and acceptance test criteria. Developers can then map the stories and criteria on their test code to verify application behavior and report results in the same common language.

Further

  • https://en.wikipedia.org/wiki/Exploratory_testing - an approach to software testing that is concisely described as simultaneous learning, test design and test execution. Cem Kaner, who coined the term in 1983, now defines exploratory testing as "a style of software testing that emphasizes the personal freedom and responsibility of the individual tester to continually optimize the quality of his/her work by treating test-related learning, test design, test execution, and test result interpretation as mutually supportive activities that run in parallel throughout the project."

While the software is being tested, the tester learns things that together with experience and creativity generates new good tests to run. Exploratory testing is often thought of as a black box testing technique. Instead, those who have studied it consider it a test approach that can be applied to any test technique, at any stage in the development process. The key is not the test technique nor the item being tested or reviewed; the key is the cognitive engagement of the tester, and the tester's responsibility for managing his or her time.

  • https://en.wikipedia.org/wiki/Error_guessing - a test method in which test cases used to find bugs in programs are established based on experience in prior testing. The scope of test cases usually rely on the software tester involved, who uses past experience and intuition to determine what situations commonly cause software failure, or may cause errors to appear.
  • https://en.wikipedia.org/wiki/Session-based_testing - a software test method that aims to combine accountability and exploratory testing to provide rapid defect discovery, creative on-the-fly test design, management control and metrics reporting. The method can also be used in conjunction with scenario testing. Session-based testing was developed in 2000 by Jonathan and James Bach. Session-based testing can be used to introduce measurement and control to an immature test process and can form a foundation for significant improvements in productivity and error detection. Session-based testing can offer benefits when formal requirements are not present, incomplete, or changing rapidly.
  • https://en.wikipedia.org/wiki/Scenario_testing - a software testing activity that uses scenarios: hypothetical stories to help the tester work through a complex problem or test system. The ideal scenario test is a credible, complex, compelling or motivating story the outcome of which is easy to evaluate. These tests are usually different from test cases in that test cases are single steps whereas scenarios cover a number of steps. Kaner coined the phrase scenario test by October 2003. He commented that one of the most difficult aspects of testing was maintaining step-by-step test cases along with their expected results. His paper attempted to find a way to reduce the re-work of complicated written tests and incorporate the ease of use cases.
  • https://en.wikipedia.org/wiki/Scenario_(computing)


  • https://en.wikipedia.org/wiki/Performance_engineering
  • https://en.wikipedia.org/wiki/Software_performance_testing - testing performed to determine how a system performs in terms of responsiveness and stability under a particular workload. It can also serve to investigate, measure, validate or verify other quality attributes of the system, such as scalability, reliability and resource usage. Performance testing is a subset of performance engineering, an emerging computer science practice which strives to build performance into the implementation, design and architecture of a system.

Tools

See also WebDev#Testing

  • Watir - pronounced water, is an open-source (BSD) family of Ruby libraries for automating web browsers. It allows you to write tests that are easy to read and maintain. It is simple and flexible. Watir drives browsers the same way people do. It clicks links, fills in forms, presses buttons. Watir also checks results, such as whether expected text appears on the page. Watir is a family of Ruby libraries but it supports your app no matter what technology it is developed in. Whilst Watir supports only Internet Explorer on Windows, Watir-WebDriver supports Chrome, Firefox, Internet Explorer, Opera and also running in headless mode (HTMLUnit). Like other programming languages, Ruby gives you the power to connect to databases, read data files and spreadsheets, export XML, and structure your code as reusable libraries.
  • WatiN - Web Application Testing In .Net. Inspired by Watir development of WatiN started in December 2005 to make a similar kind of Web Application Testing possible for the .Net languages


Documentation



UI markup

UML

XUL

  • XUL (/ˈzuːl/ zool), which stands for XML User Interface Language, is a user interface markup language that is developed by the Mozilla Project. XUL is implemented as an XML dialect; it allows for graphical user interfaces to be written in a similar manner to Web pages.

Audio

Graphics

3D

Compression

Network

Data science and stats

See also Open data, Visualisation

  • School of Data works to empower civil society organizations, journalists and citizens with the skills they need to use data effectively in their efforts to create more equitable and effective societies.
  • Kaggle - Service - From Big Data to Big Analytics.

Machine learning


Gaming

For kids

Social

Quantum

History


Cool

Humour

to sort

  • The language of languages - explains grammars and common notations for grammars, such as Backus-Naur Form (BNF), Extended Backus-Naur Form (EBNF) and regular extensions to BNF.




  • RRDtool is the OpenSource industry standard, high performance data logging and graphing system for time series data. RRDtool can be easily integrated in shell scripts, perl, python, ruby, lua or tcl applications.






modelling;

  • QEforge is a web portal offering support to researchers active in the field of computer simulation and numerical modeling of matter and materials at the atomic scale. The most popular source code management (CVS, SVN or Git ) systems, mailing lists, public forums, download space, wiki pages, and much more are provided through the Gforge engine.
  • UbiGraph is a tool for visualizing dynamic graphs. The basic version is free, and talks to Python, Ruby, PHP, Java, C, C++, C#, Haskell, and OCaml.
  • Hunspell is the spell checker of LibreOffice, OpenOffice.org, Mozilla Firefox 3 & Thunderbird, Google Chrome, and it is also used by proprietary software packages, like Mac OS X, InDesign, memoQ, Opera and SDL Trados.


  • NuPIC - the Numenta Platform for Intelligent Computing, comprises a set of learning algorithms that were first described in a white paper published by Numenta in 2009. The learning algorithms faithfully capture how layers of neurons in the neocortex learn.





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