Glossary

"When words are unfit, speech is unadapted and actions are unsuccessful"

Confucius

"When I use a word," Humpty Dumpty said in rather a scornful tone, "it means just what I choose it to mean-neither more nor less."
"The question is," said Alice, "whether you can make words mean so many different things."
"The question is," said Humpty Dumpty, "which is to be master-that's all."

Lewis Carroll, Through the Looking Glass

Do not hesitate to ask for explanations regarding a word that isn't in this Glossary yet, or whose current definition you're not satisfied with.

This glossary tries to explain the actual meaning of words related to the world of computers and operating systems, beyond slogans and myths. When multiple meanings exist, it explains which is used in the Tunes project.

This document is also laden with our political and technical opinions (computer-wise), and tries to expose whatever point of view we may have on the described words and concepts. For this reason, partiality and incorrectness may have slipped in it many times. However, we would both like to improve our point of view, and to delimitate it from raw established facts, in as much as such things exist. Hence, please correct any error, inexactitude, confusion, or misguiding style that you find in this document. Also, to add an entry, use the topic "term" for the node.

Please also note that some project members have expressed reservations about some definitions given for some words with political connotations that exceed the computer world.

All terms. All political terms. All acronyms.

Here are all the non-political terms:

• Abstract Syntax Tree - A syntax term describing object graphs which describe the meaningful attributes and behavior of expressions in a particular concrete syntax
• Abstraction - The term for the process of by which an object is taken out of its context, so that a new context can be applied to it
• Abstraction Inversion - A term for what happens when program designers try to build simple things on top of complex "primitives" instead of building the complex things on top of simple primitives
• Abstraction Level - A term, informally denoting an ordering between different possible abstract representations of a common domain
• Active - A term for objects which have side effects, otherwise objects are passive or pure
• Actor - The term for a paradigm of programming which models computations with concurrent (possibly transparently-distributed) entities, the Actors, that communicate with asynchronous messages; Actors may update their behaviour depending on the messages they receive
• Agent - A user interface term for a unit of migratable control that is often dedicated to a specific domain or class of tasks
• Algebra and coalgebra - Algebra and coalgebra are terms used to describe some classes of mathematical structures which are commonly met in mathematics and in computer science
• Animation - A user interface term for sequential display of graphics, intended to capitalize on the human visual ability to provide an understanding of the collection in a continuous form
• Artificial Intelligence - A term with at least two intended meanings:
• Aspect-Oriented Programming - The term for a means of metaprogramming where a programming language is separated into a core language and various domain-specific languages which express (ideally) orthogonal aspects of program behavior
• Assembly - At the heart of computer is traditionally a piece of electronic circuitry that executes instructions in sequence, as fetched from memory where they are encoded in bit patterns
• Aware - A term, the opposite of transparent
• Bisimulation - A term that denotes a kind of relationship on the carrier of a coalgebra and which is dual to congruence
• Bit - A term whose name is the contraction of "binary digit", is the maximal amount of information of a system that has two possible states (which maximum is reached when the two states are equally probable)
• Bootstrap - A term for the issue of, or for a specific technique for, bringing a system in a desired state by means of a (simple, rough, ad-hoc) subsystem which can perform the task with no external aid, and which is usually discarded as the global desired state has been reached
• Bus - The term for a shared communications medium, derived from the common usage of the term in computer architecture jargon
• Buzzword - A term describing other terms used to make sentences longer and more ambiguous; in this respect they strictly oppose jargon
• Capability - A security term describing a way of controlling access dynamically in a computing system by treating access to objects as provided by a "key" instead of via an "ID Card" (user rights)
• Category Theory - The term for a very abstract (often too abstract for most) theory in mathematics relating several fields through some common properties
• Centralized - The term for systems that exhibit a centralization pattern
• Channel - Channel is a term for a structure through which data is sent from one object to another
• Client - A term related to centralization
• Code Generation - The term for the last phase of a compiler that emits code in the target language
• Collection-Oriented - aka data parallel: the term for a paradigm of programming that involves operations on entire collections and avoids loops
• Combinator - A term commonly used in functional programming languages to indicate a class of higher-order functions accepting other functions as inputs
• Communication - The term for transfer or flow of information
• Computing System - A term for a system that allows men to do computations
• Computing World - The term for the concept encompassing all computers in the world, that are considered as being running different versions of a common Operating System, and linked to a global network
• concatenative - The term for a sub-paradigm of programming in which function composition is rendered syntactically as concatenation (composition, juxtaposition) of symbols by means of a composition operator, usually rendered as a blank space
• Concurrency - The term for the property of some collection of active processes that allows them to be active at any time, including at the same time, or in varying orders
• Concurrency-Oriented - A term describing a programming language paradigm where independent parts of the problem can be represented as independent computations
• Concurrent - The term for a programming language which directly supports concurrency within its core semantics, unlike for example C and C++ where concurrency must be provided by a library
• Configuration - The term for a meta-object representing some "state of affairs": requirements on the relationships between some collection of objects
• Congruence - A term that denotes a class of relationships between algebras and which is dual to bisimulation
• Constraints - The term for a paradigm related to logic or declarative programming, where information is specified as a constraint on the result, and the evaluator's task is to use this information to limit the search space that some base set of algorithms would ordinarily have traversed to find the answer
• Constructor and Destructor - In computer terminology, a constructor is some function that takes a list of parameter objects and makes a new object out of these by assembling them into a structure
• Context - The term for that which gives, or completes, the meaning of an object
• Continuation - A term from functional programming where a function is used to capture the whole of the rest of the computation from a specific point in the lexical scope
• Correctness - A term describing a relation: a program is said to be correct with respect to some specification if it fulfills all the constraints of this specification
• Cybernetics - A term for the science of information, that is, of what makes dynamical systems and meta-systems
• Decentralized - The contrasting term to centralized: not obeying to a one guide, chief, führer, duce, central committee, or any other kind of grand beloved all-mighty all-knowing (individual or collective) leader
• Declarative - The term for a paradigm of programming where the specification allows for a great deal of freedom in acheiving results as specified; we say that a declarative program specifies the "what" of the result, but not the "how"; programming languages which encourage this style of programming are termed declarative, and specifically include the logic and functional paradigms, to varying degrees
• Dependent Types - A term describing a type system where types can depend on values
• Design Pattern - A term for describing how a solution framework is often not supported by underlying programming languages
• Diagram - A user interface term for a representation of some group of information that at least partially makes use of structural or symbolic representation
• Dispatch - The term and topic of a programming language's method of choosing a definition to use to evaluate some expression
• Distributed - A term describing a networked computer system which is able to dynamically dispatch information around the whole network of available workstations or subsystems, automatically, according to demand
• Domain-Specific Language - The term for a programming language designed for a special purpose, usually within some commercial field of application, although such a language can be made for practically any domain
• Duality - The term for a dichotomy or a division in a space of possibilities
• Dynamic - A term which applies to what possesses Dynamism
• Dynamic Compilation - The term for the dynamic construction of code while other code in the same system is being evaluated
• Dynamism - The term for the notion according to which the world constantly changes and evolves, and that no static analysis can be indefinitely valid
• Efficient - A term generally used to mean fast, optimized, or non-wasteful when referring to programs, algorithms, or programming languages (if it has low overhead)
• End-Users - According to the silly notions of traditional systems, a term for some category of people, for whom computers would be made, but who for whatever reason would not learn about the technical details in any manner
• Entropy - The term for the opposite of information
• Epsilon Calculus - A formal logic term
• Equality - The term for a relation among objects within a given context determining their comparitive identity - whether they are the same or different from a given perspective
• Escape - A term for a way to exit the current or normal context
• Expressiveness - A term for a comparative quality of a language:
• Fault-tolerant - The term for the ability of a system to continue normal operation despite the presence of hardware or software faults
• Feature-Oriented Programming - The term for a kind of metaprogramming
• Feedback - The term for the mechanism by which information can stabilize, propagate, and evolve in a dynamic system: subsystems correct their output according to the input they get back from the "external world" after
• File System - The term for a low-level programming model for persistent data storage
• First-Order - The term for contexts in which only objects of a theory may be abstracted
• Foreign Function Interface - The term for the means for a language to access code written in other languages (see Combining Languages)
• Functional - The term for a paradigm of programming that originates in the early works about lambda calculus: computations consist in evaluating/expanding structured expressions, rather than executing instructions, as with imperative programming
• Future - The term for a place-holder for the undetermined result of a (concurrent) computation
• Garbage Collection - The term for automated memory-management and reclamation, one of the many methods of migration
• Grain - A term for the minimal or typical size of objects a system can handle
• Graph Reduction - A technical term, taken from its FOLDOC entry:
• handshaking - A term describing a simple synchronization scheme between two connected objects (programs, devices, or computer systems), which is usually designed to ensure that the two objects 'take turns' at communicating with each other
• Hardware-Independent - A comparative term for software which has a higher abstraction level with respect to the underlying hardware
• High-Level - A term describing a comparatively-suitable end of a spectrum of abstraction levels for the context that requires the abstractions
• Higher-Order - The term for a context in which any kind of abstractions are recursively possible over a system
• highly concurrent - A term for a program or system whose software is designed to execute as a relatively large number of threads, so as to interact more efficiently with the outside environment (the user, I/O devices, other software or system components)
• Host - A standard term for the basic entity in a computer network: each computer in the network is typically called a "host"
• Hypertext - A user interface term coined by Ted Nelson? to discuss text as a medium extended to support any kinds of internalized references to other pieces of text
• Imperative - The term for a paradigm of programming that involves (mostly unconstrained) update of the state of a machine through direct instructions
• Induction and Co-induction - These are contrasting terms for ways of describing a system
• Information - A term for the measure of the improbability of the known state of a system
• Initiality and finality - These terms indicate dual concepts in category theory
• Input - A term for what is consumed by an open system
• Interoperability - The term for a number of different entities being able to speak the same language
• Isolation - A term for when a computer object is not secure, it must be isolated from possible sources of failure
• Jargon - Jargon are a collection of terms that have a precise meaning in a given technical or cultural context, and that help people of a given milieu communicate in a precise and concise way
• Kernel - The term for any "central" part in a software program
• Lambda Calculus - The term for the mathematically formalized theory of abstractions
• Language - The term for a medium of expression, which consists of a vocabulary, some semantics, and a syntax for accessing the semantics
• Language-Based Security - The term for an approach to security which relies on the properties of a programming language in which programs are written to ensure that promises are not violated
• Lazy Evaluation - The term for a strategy? to evaluate objects only when one is sure they are useful or needed, and not before
• LifeStreams - A user interface term: it is a stream of information chunks to organize the way a person deals with other people; in much the same manner as an electronic diary, the chronological arrangement is key, but the information can be organized in many other ways
• Linear Algebra - In any generalized algebra, that is, a structure with a commutative associative sum operation with neutral element over which other "product" operations distribute, a functional term is said to be linear in some variable if and only if this term can be expressed as a sum of "monomials" in each of which the variable appears (exactly) once
• Linear Graph Reduction - The term for a variation on traditional graph reduction where the availability of references obeys a linear logic in its type
• Linear Logic - Linear Logic, which started as a theoretical endeavor in proof theory, is now a theme of study of its own
• load balancing - A term describing any mechanism for automatically redistributing computational work (the 'load') among available processing resources, so that better (or the best) use is made of those resources
• Logic - The term for a paradigm of programming that originates in the Curry-Howard Isomorphism, which relates types and proofs to terms and expressions
• Low-Level - A term for contexts that are less adapted to a problem in the context of abstraction levels
• Macro - The term for a way to extend the syntax and semantics of a programming language; they are a special case of compile-time rewrite
• Man - The term for some fragile machine that takes several tens of years to manufacture, with a low success rate, and only seconds to get definitely out-of-order
• Marshalling - The term for encoding high-level data-structures so they fit the sequence-of-bytes (or sequence-of-words) paradigm used in low-level message-passing paradigms
• Memory - The computer term for the maximum amount of information it can handle, as measured in bits
• Meta- - A prefix term that means beyond or after (spatially)
• Meta-Circular - A term describing an interpreter for a language L written in the same language L (or a subset thereof), said to be a meta-circular interpreter
• Meta-Level - The Meta-level is a relative term for any object, describing the level of discourse about that object; the objects of the metalevel (or metaobjects) are sentences or programs that are used to describe and manipulate objects at the original ("base") level
• Meta-Object - The term for an object whose sole focus of attention is another object
• Meta-Object Protocol - A term for, simply stated, a set of rules for manipulating and communicating with meta-objects
• Meta-Space - An object is defined in a space, in a context
• Meta-System Transition - The term for a theory being settled down by the
• Metaprogramming - Meta-programming is the term for the art of developing methods and programs to read, manipulate, and/or write other programs
• Metatext - A term coined within the Tunes Interfaces subproject for the use of higher-order objects to deal with and relate hypertext systems
• Microkernel - Microkernel (also abbreviated µK or uK) is the term describing an approach to Operating System design by which the functionality of the system is moved out of the traditional "kernel", into a set of "servers" that communicate through a "minimal" kernel, leaving as little as possible in "system space" and as much as possible in "user space"
• Microkernel Debate - This is a debate on Microkernels
• Migration - The term for the phenomenon whereby the representation for an object is changed while conserving the abstract object consistently unchanged
• Modal - Modal is a user interface term, but it is applied from the field of logic, where a mode means a situation where only a finite set of possibilities for transitioning into the future are possible
• Module - A term for a component of a system with a well-defined interface
• Monad - A term taken from category theory and applied to functional programming concepts to provide a way to deal with local, single-thread state in a functional language without having to pass the state around explicitly as extra arguments to all the functions that deal with it (and requiring changing their signatures, etc.) See also Eugenio Moggi and a Learning Lounge course, Monads 101
• Morphism - A term related to category theory describing a map between two objects in an abstract category
• Network - The term for a system all of whose members are networked
• Networked - For an entity in a system, the term for being linked to other entities, that is, there being input and output between the entity and others, faster than the speed that the entity can stabilize
• No-Kernel - A term describing a system without a kernel
• Non-Well-Founded - A term for systems that are not well-founded, meaning that they are not based strictly on a few independent principles
• Object - A unified term to manipulate computer abstractions
• Object-Oriented - A paradigm of programming
• Ontology - In philosophy the term ontology is used to indicate a theory of being, which describes "what is" and in some cases by converse "what is not", and the relationships between beings
• Open Implementation - The term for an implementation that can be dynamically (at run-time or otherwise post facto) evolved, customized, modified, etc
• Operating System - In the TUNES project, the term for any common cultural background between different computers
• Optimize - In the commercial jargon, the term "to optimize" means to make better, quicker, smaller, less expensive, more efficient
• Optimizer - The term for optimizing code generation
• Orthogonal - A term: we say that A is orthogonal to B if you don't have to think about feature A while thinking about feature B
• Orthogonal Persistence - The term for a system's property in which objects persist until they are no more needed, neither before, which would make the system fail, nor after, which would waste (eventually all) the system's limited resources
• Output - The term for what is produced by an open system
• Overhead - The term for unproductive expense
• Paradigm - A term for a way of exposing concepts and things; see also Programming Languages for a list of programming paradigms
• Parsing - The term for the process of turning an input stream into an abstract syntax tree
• Partial Evaluation - A term for the metaprogramming technique that consists in program transformation into simpler programs specialized for execution in an environment where some information is known as compared to a generic environment
• Passive - A term for objects which are not active
• Pattern-Matching - A term used to describe a family of programs operating over compound, structured data, usually trees or graphs
• Performance - The term for the inverse of the quantity of resources consumed by a computation, as defined by some metric
• Persistence - A term for a system in which any object consistently preserves its informational content across some expectable stressing modification, and more generally accross all the modifications that time is likely to bring
• Portability - The term for a system or object describing the fact that communication is as easy as possible for it
• Process - The term within traditional operating systems for a very coarse-grained active object
• process migration - A term for the ability of a distributed operating system to move processes from one workstation or subsystem to another around the network, automatically, according to demand
• Programming Language - A topic for programming languages, a term for computational languages that are at least as expressive as the lambda calculus
• Proof - A term for the process of checking that a belief holds in some context
• Proof-Carrying Code - The term for a type of program or module that carries a verifiable specification of its behavior as it is migrated between contexts
• Protection - The term for a common low-level paradigm for security, in
• prototype-based - A term describing an object-oriented sub-paradigm, which contrast class-based
• Pure - A term for actions or things with no side effect
• Quine - The term for a sentence that describes itself
• Quotienting - A term from logic for a type of abstraction which takes a class of objects according to some set of rules, providing new identities for objects that are identical according to those rules
• Rational - The term for that which relies on and trusts reason, acknowledges the truth that reason reveals, but also acknowledges the limits of what reason can reveal
• Real-Time - Real time is a term that pertains to the responsiveness of a system wich is sufficiently immediate or that enables it to keep up with some external process
• Reference - The term for an abstraction of the use of an object
• Referential Transparency and State - A pair of terms characterizing two useful ways of looking at a computing system:
• Reflection - Etymologically, reflection is first a term about turning back the image of another object; since the phenomenon was mostly used to see oneself with mirrors (the alternate spelling reflexion is preferred for the optical phenomenon), it has come to mean applying to oneself (see reflexive)
• Reflective Tower - The term for a chain of meta-levels or meta-system transitions which at some point enters a recursion possibility
• Reflexive - While having same etymology as Reflection, the term Reflexive means to apply or to refer to oneself
• Reification - Reification is the term for an operation by which something that was previously implicit, unexpressed and possibly unexpressible is explicitly formulated and made available to conceptual (logical or computational) manipulation
• Relational - The term for a paradigm of programming where relationships between objects are formalized as Relation objects
• Resilient - The term for resistant to problems and surviving failures
• Rewrite - The term for replacement of strings, terms, trees, or other forms of expression according to logical rules, particularly as a form of evaluation semantics
• Run-Time Code Generation - The term for code generation by a running program (run-time)
• Scope - The term for a concept abstracted from the lexical or dynamic scope concept in most programming languages
• Security - Security is the term we take as the dual concept of liberty: while liberty is potential information, security is actual information
• Self-extensible - The term describing a cybernetic system that is powerful enough to accomplish some kind of meta-system transition: a way to abstract from some issue in a system-wide scope
• Semantics - The term that applies in various ways to describe what the programs of a language mean
• Sequential Machine - The term for the usual way to conceive single units of computations, as modelled by Von Neumann in the 1940's
• Serializing - The modern term for Marshalling
• Server - In a centralized organization, the term for the central (commanding) entity, which responds to requests for information
• Side Effect - A term: an operation is said to have side effects if it modifies the context in which it is executed
• Static - A term for an object that doesn't move or change, that is, is not dynamic
• Statism - The term for the notion that the world is essentially static, that is, doesn't change significantly
• Super-User - The term for human users who are given all the power on the system, in some system-management policies
• Syntax - The term and topic of the structure of expressions in a language
• Tactic - A term derived from Coq's usage of it meaning a program which operates on a declarative system in a procedural manner
• Terminal - The user interface term which, for the purposes of Tunes, is the combination of any output device and any input device
• Thread - In Tunes, the term for any kind of object that can be considered semantically as a logical unit of execution, from a light-weight continuation being evaluated to a number of coarse-grained unixish processes, including interrupt handling code, etc
• Time-Machine Computing - A user interface term for a time-centric approach to organizing information on computers; it differs from LifeStreams in the use of both time and spatial (2D desktop) dimensions (where for LifeStreams the spatial dimension is not meaningful, it is automatically managed)
• Transparent - A term indicating a feature of a software component whose behavior, i
• Trust - When there's some statistical likelihood based on observations alone, then when the subject acts on the information that's just statistically-likely, then we use the term that the subject is trusting that the information is the case
• Type - Typing in general means that the choice of possible data structures manipulated by a program can be conceptually divided into groups of objects with some homogeneity (e.g. integers, floating-point numbers, lists, arrays, hash-tables, etc.); the term for these groups is called a type
• Type System - Programming languages usually come with a type-system, a term for some algebraic structure whose elements are the types of data that can be manipulated in the language, together with a mapping from the set of objects involved in defining the semantics of the language into the typesystem
• Unification - A term generalizing that of pattern-matching that is the logic programming equivalent of instantiation in logic
• Unified - Our term for the notion that all computer abstractions are equal, and may equally be subject to any operation, without any arbitrary prejudice or discrimination, including "code" vs "data", or "persistent" vs "transient"
• Uniform - A term which applies to what is unified
• User - The term for someone who uses a computer or a piece of software, or whatever, in any way
• User Rights - Traditional systems enforce a "security" paradigm of a finite number of users, each controlling his own files, and having no right (a semi-legal term) on those from others
• Utilitarianism - Utilitarianism is the term for a philosophy that places an absolute concept of Utility, (relatively to some notion of Good), as ultimately the only direct or indirect moral end
• Utility - We say that something is useful if and only if it improves the world
• Version-Aware - This term expresses that a system where multiple and concurrent modifications of an object can be expressed as their own unique objects
• Virtual Machine - The term for a machine (computing system) that is designed for and intended to be used only as software within another machine
• Visible - Visible is a User Interface term
• Well-Founded - A term for systems that are built inductively, starting from a small core and calling constructors on it
• World - A term for any system considered closed

Other related glossaries (may disagree with ours)

• American National Standard Dictionary of Information Technology (ANSDIT)
• The Jargon File aka The New Hacker's Dictionary.
• The Common Lisp HyperSpec (CLHS) defines a large vocabulary in order to work with the range of concepts that it does.
• The Principia Cybernetica Project's glossary of terms related to memetics.
• FOLDOC.
• The Wikipedia area for Computer Science
• The Devil's Dictionary by Ambrose Bierce is funny if you don't take it seriously, even though it has nothing in particular to do with the TUNES project.
• [MIA] Sun's glossary of computer terms, very low-level and SunOS centered (551k).
• An Engineering Glossary (mirror)
• Factasia.
• The Stanford Encyclopedia of Philosophy.

Bibliography

• On liberty.

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