Purely functional programmingIn computer science, purely functional programming usually designates a programming paradigm—a style of building the structure and elements of computer programs—that treats all computation as the evaluation of mathematical functions. Program state and mutable objects are usually modeled with temporal logic, as explicit variables that represent the program state at each step of a program execution: a variable state is passed as an input parameter of a state-transforming function, which returns the updated state as part of its return value.
Generalized algebraic data typeIn functional programming, a generalized algebraic data type (GADT, also first-class phantom type, guarded recursive datatype, or equality-qualified type) is a generalization of parametric algebraic data types. In a GADT, the product constructors (called data constructors in Haskell) can provide an explicit instantiation of the ADT as the type instantiation of their return value. This allows defining functions with a more advanced type behaviour.
Class-based programmingClass-based programming, or more commonly class-orientation, is a style of object-oriented programming (OOP) in which inheritance occurs via defining classes of objects, instead of inheritance occurring via the objects alone (compare prototype-based programming). The most popular and developed model of OOP is a class-based model, instead of an object-based model. In this model, objects are entities that combine state (i.e., data), behavior (i.e., procedures, or methods) and identity (unique existence among all other objects).
CoqCoq is an interactive theorem prover first released in 1989. It allows for expressing mathematical assertions, mechanically checks proofs of these assertions, helps find formal proofs, and extracts a certified program from the constructive proof of its formal specification. Coq works within the theory of the calculus of inductive constructions, a derivative of the calculus of constructions. Coq is not an automated theorem prover but includes automatic theorem proving tactics (procedures) and various decision procedures.
Is-aAn is-a relationship is when one type of object 'is a' instance of another type of object. For example, a cat 'is a' animal, but not vice versa. All cats are animals, but not all animals are cats. The concept becomes important in object oriented programing, where 'is a' relationships are often used as a way to structure code - behaviour that are is relevant to all animals is defined on an animal class, whereas behaviour that is relevant only for cats is defined in a cat class.
Oberon (programming language)Oberon is a general-purpose programming language first published in 1987 by Niklaus Wirth and the latest member of the Wirthian family of ALGOL-like languages (Euler, ALGOL W, Pascal, Modula, and Modula-2). Oberon was the result of a concentrated effort to increase the power of Modula-2, the direct successor of Pascal, and simultaneously to reduce its complexity. Its principal new feature is the concept of type extension of record types.
Top typeIn mathematical logic and computer science, some type theories and type systems include a top type that is commonly denoted with top or the symbol ⊤. The top type is sometimes called also universal type, or universal supertype as all other types in the type system of interest are subtypes of it, and in most cases, it contains every possible object of the type system. It is in contrast with the bottom type, or the universal subtype, which every other type is supertype of and it is often that the type contains no members at all.
Visitor patternA visitor pattern is a software design pattern and separates the algorithm from the object structure. Because of this separation new operations can be added to existing object structures without modifying the structures. It is one way to follow the open/closed principle in object-oriented programming and software engineering. In essence, the visitor allows adding new virtual functions to a family of classes, without modifying the classes. Instead, a visitor class is created that implements all of the appropriate specializations of the virtual function.
Total functional programmingTotal functional programming (also known as strong functional programming, to be contrasted with ordinary, or weak functional programming) is a programming paradigm that restricts the range of programs to those that are provably terminating. Termination is guaranteed by the following restrictions: A restricted form of recursion, which operates only upon 'reduced' forms of its arguments, such as Walther recursion, substructural recursion, or "strongly normalizing" as proven by abstract interpretation of code.
Adapter patternIn software engineering, the adapter pattern is a software design pattern (also known as wrapper, an alternative naming shared with the decorator pattern) that allows the interface of an existing class to be used as another interface. It is often used to make existing classes work with others without modifying their source code. An example is an adapter that converts the interface of a Document Object Model of an XML document into a tree structure that can be displayed.
