Multiple dispatch

About: Multiple dispatch is a research topic. Over the lifetime, 167 publications have been published within this topic receiving 6505 citations.

Julia: A Fresh Approach to Numerical Computing

Abstract: Bridging cultures that have often been distant, Julia combines expertise from the diverse fields of computer science and computational science to create a new approach to numerical computing. Julia is designed to be easy and fast and questions notions generally held to be “laws of nature" by practitioners of numerical computing: \beginlist \item High-level dynamic programs have to be slow. \item One must prototype in one language and then rewrite in another language for speed or deployment. \item There are parts of a system appropriate for the programmer, and other parts that are best left untouched as they have been built by the experts. \endlist We introduce the Julia programming language and its design---a dance between specialization and abstraction. Specialization allows for custom treatment. Multiple dispatch, a technique from computer science, picks the right algorithm for the right circumstance. Abstraction, which is what good computation is really about, recognizes what remains the same after dif...

Julia: A Fresh Approach to Numerical Computing

Abstract: Bridging cultures that have often been distant, Julia combines expertise from the diverse fields of computer science and computational science to create a new approach to numerical computing. Julia is designed to be easy and fast. Julia questions notions generally held as "laws of nature" by practitioners of numerical computing: 1. High-level dynamic programs have to be slow. 2. One must prototype in one language and then rewrite in another language for speed or deployment, and 3. There are parts of a system for the programmer, and other parts best left untouched as they are built by the experts. We introduce the Julia programming language and its design --- a dance between specialization and abstraction. Specialization allows for custom treatment. Multiple dispatch, a technique from computer science, picks the right algorithm for the right circumstance. Abstraction, what good computation is really about, recognizes what remains the same after differences are stripped away. Abstractions in mathematics are captured as code through another technique from computer science, generic programming. Julia shows that one can have machine performance without sacrificing human convenience.

Common Lisp Object System specification

Abstract: IntroductionThe Common Lisp Object System is an object-oriented extension to Common Lisp as defined in Common Lisp: The Language, by Guy L. Steele Jr. It is based on generic functions, multiple inheritance, declarative method combination, and a meta-object protocol.The first two chapters of this specification present a description of the standard Programmer Interface for the Common Lisp Object System. The first chapter contains a description of the concepts of the Common Lisp Object System, and the second contains a description of the functions and macros in the Common Lisp Object System Programmer Interface. The chapter "The Common Lisp Object System Meta-Object Protocol" describes how the Common Lisp Object System can be customized.The fundamental objects of the Common Lisp Object System are classes, instances, generic functions, and methods.A class object determines the structure and behavior of a set of other objects, which are called its instances. Every Common Lisp object is an instance of a class. The class of an object determines the set of operations that can be performed on the object.A generic function is a function whose behavior depends on the classes or identities of the arguments supplied to it. A generic function object contains a set of methods, a lambda-list, a method combination type, and other information. The methods define the class-specific behavior and operations of the generic function; a method is said to specialize a generic function. When invoked, a generic function executes a subset of its methods based on the classes of its arguments.A generic function can be used in the same ways that an ordinary function can be used in Common Lisp; in particular, a generic function can be used as an argument to funcall and apply and can be given a global or a local name.A method is an object that contains a method function, a sequence of parameter speclalizers that specify when the given method is applicable, and a sequence of qualifiers that is used by the method combination facility to distinguish among methods. Each required formal parameter of each method has an associated parameter specializer, and the method will be invoked only on arguments that satisfy its parameter specializers.The method combination facility controls the selection of methods, the order in which they are run, and the values that are returned by the generic function. The Common Lisp Object System offers a default method combination type and provides a facility for declaring new types of method combination.

Rethinking the Computer Music Language: SuperCollider

Abstract: ion Description and Purpose Variable names Provide human readable names to data addresses Function names Provide human readable names to function addresses Control structures Eliminate ‘‘spaghetti’’ code (The ‘‘goto’’ statement is no longer necessary.) Argument passing Default argument values, keyword specification of arguments, variable length argument lists, etc. Data structures Allow conceptual organization of data Data typing Binds the type of the data to the type of the variable Static Insures program correctness, sacrificing generality. Dynamic Greater generality, sacrificing guaranteed correctness. Inheritance Allows creation of families of related types and easy re-use of common functionality Message dispatch Providing one name to multiple implementations of the same concept Single dispatch Dispatching to a function based on the run-time type of one argument Multiple dispatch Dispatching to a function based on the run-time type of multiple arguments. Predicate dispatch Dispatching to a function based on run-time state of arguments Garbage collection Automated memory management Closures Allow creation, combination, and use of functions as first-class values Lexical binding Provides access to values in the defining context Dynamic binding Provides access to values in the calling context (.valueEnvir in SC) Co-routines Synchronous cooperating processes Threads Asynchronous processes Lazy evaluation Allows the order of operations not to be specified. Infinitely long processes and infinitely large data structures can be specified and used as needed. Applying Language Abstractions to Computer Music The SuperCollider language provides many of the abstractions listed above. SuperCollider is a dynamically typed, single-inheritance, single-argument dispatch, garbage-collected, object-oriented language similar to Smalltalk (www.smalltalk.org). In SuperCollider, everything is an object, including basic types like letters and numbers. Objects in SuperCollider are organized into classes. The UGen class provides the abstraction of a unit generator, and the Synth class represents a group of UGens operating as a group to generate output. An instrument is constructed functionally. That is, when one writes a sound-processing function, one is actually writing a function that creates and connects unit generators. This is different from a procedural or static object specification of a network of unit generators. Instrument functions in SuperCollider can generate the network of unit generators using the full algorithmic capability of the language. For example, the following code can easily generate multiple versions of a patch by changing the values of the variables that specify the dimensions (number of exciters, number of comb delays, number of allpass delays). In a procedural language like Csound or a ‘‘wire-up’’ environment like Max, a different patch would have to be created for different values for the dimensions of the patch.

MultiJava: modular open classes and symmetric multiple dispatch for Java

Abstract: We present MultiJava, a backward-compatible extension to Java supporting open classes and symmetric multiple dispatch. Open classes allow one to add to the set of methods that an existing class supports without creating distinct subclasses or editing existing code. Unlike the "Visitor" design pattern, open classes do not require advance planning, and open classes preserve the ability to add new subclasses modularly and safely. Multiple dispatch offers several well-known advantages over the single dispatching of conventional object-oriented languages, including a simple solution to some kinds of "binary method" problems. MultiJava's multiple dispatch retains Java's existing class-based encapsulation properties. We adapt previous theoretical work to allow compilation units to be statically typechecked modularly and safely, ruling out any link-time or run-time type errors. We also present a n compilation scheme that operates modularly and incurs performance overhead only where open classes or multiple dispatching are actually used.