Ease (programming language)

Infobox programming language
name = Ease
logo =
paradigm = concurrent
year = 1990
designer = Steven Ericsson-Zenith
developer =
latest release version =
latest release date =
typing =
implementations = various
dialects = C-with-Ease, Carnap
influenced_by = Communicating Sequential Processes, occam, Linda
influenced =

Ease is a general purpose parallel programming language, designed by Steven Ericsson-Zenith of Yale University. It combines the process constructs of CSP with logically shared data structures called "contexts". Contexts are parallel data types that are constructed by processes and provide a way for processes to interact.

The language includes two process constructors.

A "cooperation" includes an explicit barrier synchronization and is written:

::$parallel\; P()\; parallel\; Q()\; ;$

If one process finishes before the other then it will wait until the other processes are finished.

A "subordination" creates a process that shares the "contexts" that are in scope when created and finishes when complete (it does not wait for other processes) and is written:

::

Subordinate processes stop if they attempt to interact with a "context" that has completed because the parent process has stopped. This enables speculative processes to be created that will finish if their result is not needed.

Powerful "replication" syntax allows multiple processes to be created. For example

::$parallel\; \{i\};\; \{for\};\; \{n\}\; :\; P()\; ;$

creates "n" synchronized processes each with a local constant "i".

Processes cannot share "local" variables and cooperate in the construction of shared "contexts." Certain context types, called "resources", ensure call-reply semantics.

There are four functions upon contexts:

* read ( context, variable ), copies a value from the shared "context" to the "variable".
* write ( context, expression ), copies the value of "expression" to the shared "context".
* put ( context, name ), moves the value bound to "name" to the shared "context". The value of "name" is subsequently "undefined".
* get ( context, name ), moves a value from "context" and binds it "name". The value is removed from the context.

Context types are "Singletons", "Bags" or "Streams" and can be subscripted arrays.

Ease has a "semiotic definition." This means that it takes into account the effect the language has on the programmer and how they develop algorithms. The language was designed to "ease" the development of parallel programs.

Zenith is also a designer of the parallel programming language Occam and the MPI standard. He worked at Yale University on Linda and at INMOS on the Transputer microprocessor for parallel computing. Like Occam, the definition of Ease uses CSP as its mathematical foundation. Steven Zenith is currently at the Institute for Advanced Science & Engineering in California.

References

[http://doi.ieeecomputersociety.org/10.1109/ICPADS.1998.741145 T.H. MacKenzie, T.I. Dix, "Object-Oriented Ease-Based Parallel Primitives in C++," icpads, p. 623, 1998 International Conference on Parallel and Distributed Systems (ICPADS'98), 1998]

External links

* [http://process-interaction-models.info Steven Ericsson-Zenith's web site on Process Interaction Models and Ease.]
* [http://www.carnap.info/ Carnap]