SAC (Single Assignment C) is a strict
purely functional programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
whose design is focused on the needs of numerical applications. Emphasis is laid on efficient support for
array processing
Array processing is a wide area of research in the field of signal processing that extends from the simplest form of 1 dimensional line arrays to 2 and 3 dimensional array geometries. Array structure can be defined as a set of sensors that are sp ...
via
data parallelism
Data parallelism is parallelization across multiple processors in parallel computing environments. It focuses on distributing the data across different nodes, which operate on the data in parallel. It can be applied on regular data structures like ...
. Efficiency concerns are essentially twofold. On the one hand, efficiency in program development is to be improved by the opportunity to specify array operations on a high level of
abstraction
Abstraction in its main sense is a conceptual process wherein general rules and concepts are derived from the usage and classification of specific examples, literal ("real" or "concrete") signifiers, first principles, or other methods.
"An abstr ...
. On the other hand, efficiency in program execution, i.e. the runtime performance of programs, in time and memory consumption, is still to be achieved by sophisticated
compilation
Compilation may refer to:
*In computer programming, the translation of source code into object code by a compiler
**Compilation error
**Compilation unit
*Product bundling, a marketing strategy used to sell multiple products
*Compilation thesis
M ...
schemes. Only as far as the latter succeeds, the high-level style of specifications can actually be called useful.
To facilitate compiling to efficiently executable code, certain functional language features which are not considered essential for numerical applications, e.g. higher-order functions,
polymorphism, or
lazy evaluation
In programming language theory, lazy evaluation, or call-by-need, is an evaluation strategy which delays the evaluation of an expression until its value is needed (non-strict evaluation) and which also avoids repeated evaluations (sharing).
The b ...
, are not (yet) supported by SAC. These may be found in general-purpose functional languages, e.g.
Haskell
Haskell () is a general-purpose, statically-typed, purely functional programming language with type inference and lazy evaluation. Designed for teaching, research and industrial applications, Haskell has pioneered a number of programming lang ...
,
Clean,
Miranda, or
ML.
To overcome the acceptance problems encountered by other functional or array based languages intended for numerical / array intensive applications, e.g.
SISAL
Sisal (, ) (''Agave sisalana'') is a species of flowering plant native to southern Mexico, but widely cultivated and naturalized in many other countries. It yields a stiff fibre used in making rope and various other products. The term sisal ma ...
,
NESL
NESL is a parallel programming language developed at Carnegie Mellon by the SCandAL project and released in 1993. It integrates various ideas from parallel algorithms, functional programming, and array programming languages.
The most important ne ...
,
Nial
Nial (from "Nested Interactive Array Language") is a high-level array programming language developed from about 1981 by Mike Jenkins of Queen's University, Kingston, Ontario, Canada. Jenkins co-created the Jenkins–Traub algorithm.
Nial c ...
,
APL,
J, or
K, particular regard is paid to ease the transition from a
C /
Fortran like programming environment to SAC.
In more detail, the basic language design goals of SAC are to:
* provide a purely functional language with a syntax very similar to that of C in order to ease, for a large community of programmers, the transition from an imperative to a functional programming style;
* support multi-dimensional arrays as first class objects;
* allow the specification of shape- and dimension-invariant array operations;
* provide high-level array operations that liberate programming from tedious and error-prone specifications of starts, stops and strides for array traversals thereby improving
code reusability and
programming productivity Programming productivity (also called software productivity or development productivity) describes the degree of the ability of individual programmers or development teams to build and evolve software systems. Productivity traditionally refers to th ...
, in general.
* incorporate a module system that allows for separate compilation, separate name spaces, and abstract data types, and, additionally, provides an interface to foreign languages in order to enable reuse of existing code;
* provide means for a smooth integration of states and state modifications into the functional paradigm based on uniqueness types;
* use the module system, the foreign language interface, and the integration of states in order to create a standard library which provides a functionality similar to that of the standard C libraries, e.g. powerful I/O facilities or mathematical functions;
* facilitate the compilation to host machine code which can be efficiently executed both in terms of time and space demand;
* facilitate the compilation for
non-sequential program execution in
multiprocessor
Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There ar ...
environments.
References
*
*
External links
The SAC Home Page
{{DEFAULTSORT:Sac Programming Language
Array programming languages
C programming language family