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The join-calculus is a process calculus developed at INRIA. The join-calculus was developed to provide a formal basis for the design of distributed programming languages, and therefore intentionally avoids communications constructs found in other process calculi, such as rendezvous communications, which are difficult to implement in a distributed setting. Despite this limitation, the join-calculus is as expressive as the full π-calculus. Encodings of the π-calculus in the join-calculus, and vice versa, have been demonstrated.
- Scope restriction, reception, and replicated reception are syntactically merged into a single construct, the definition;
- Communication occurs only on defined names;
- For every defined name there is exactly one replicated reception.
However, as a language for programming, the join-calculus offers at least one convenience over the π-calculus — namely the use of multi-way join patterns, the ability to match against messages from multiple channels simultaneously.
Languages based on the join-calculus
The join-calculus programming language is a new language based on the join-calculus process calculus. It is implemented as an interpreter written in OCaml, and supports statically typed distributed programming, transparent remote communication, agent-based mobility, and some failure-detection.
Many implementations of the join-calculus were made as extensions of existing programming languages:
- JoCaml is a version of OCaml extended with join-calculus primitives
- Polyphonic C# and its successor Cω extend C#
- MC# and Parallel C# extend Polyphonic C#
- Join Java extends Java
- A Concurrent Basic proposal that uses Join-calculus
- JErlang (the J is for Join, erjang is Erlang for the JVM))
Embeddings in other programming languages
These implementations do not change the underlying programming language but introduce join calculus operations through a custom library or DSL:
- The Boost.Join library is an implementation in C++ within the Boost framework
- The ScalaJoins and the Chymyst libraries are in Scala
- The "Join Language" is in Haskell
- Joinads - various implementations of join calculus in F#
- CocoaJoin is an experimental implementation in Objective-C for iOS and Mac OS X
- The Join Python library is in Python 3
- C++ via Boost
- Cedric Fournet, Georges Gonthier (1995). "The reflexive CHAM and the join-calculus"., pg. 1
- Cedric Fournet, Georges Gonthier (1995). "The reflexive CHAM and the join-calculus"., pg. 2
- Cedric Fournet, Georges Gonthier (1995). "The reflexive CHAM and the join-calculus"., pg. 19
- Cedric Fournet, Georges Gonthier (2000). "The Join Calculus: A Language for Distributed Mobile Programming".
- JErlang: Erlang with Joins
- Yigong Liu - Join-Asynchronous Message Coordination and Concurrency Library
- INRIA, Join Calculus homepage
- Microsoft Research, The Join Calculus: a Language for Distributed Mobile Programming