Chapel, the Cascade High Productivity Language, is a

parallel programming language Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different for ...

that was developed by

Cray Cray Inc., a subsidiary of Hewlett Packard Enterprise, is an American supercomputer manufacturer headquartered in Seattle, Washington. It also manufactures systems for data storage and analytics. Several Cray supercomputer systems are listed ...

, and later by

Hewlett Packard Enterprise The Hewlett Packard Enterprise Company (HPE) is an American multinational information technology company based in Spring, Texas, United States. HPE was founded on November 1, 2015, in Palo Alto, California, as part of the splitting of the H ...

which acquired Cray. It was being developed as part of the Cray Cascade project, a participant in

DARPA The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adv ...

High Productivity Computing Systems High Productivity Computing Systems (HPCS) is a DARPA project for developing a new generation of economically viable high productivity computing systems for national security and industry in the 2002–10 timeframe. The HPC Challenge (High-perfo ...

(HPCS) program, which had the goal of increasing

supercomputer A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second ( FLOPS) instead of million instructions ...

productivity by 2010. It is being developed as an

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

project, under version 2 of the Apache license. The Chapel compiler is written in C and

C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...

(

C++14 C++14 is a version of the ISO/IEC 14882 standard for the C++ programming language. It is intended to be a small extension over C++11, featuring mainly bug fixes and small improvements, and was replaced by C++17. Its approval was announced on August ...

). The backend (i.e. the optimizer) is

LLVM LLVM is a set of compiler and toolchain technologies that can be used to develop a front end for any programming language and a back end for any instruction set architecture. LLVM is designed around a language-independent intermediate represen ...

, written in C++. Python 3.7 or newer is required for some optional components such Chapel’s test system and c2chapel, a tool to generate C bindings for Chapel. By default Chapel compiles to binary expendables, but it can also compile to C code, and then LLVM is not used. Chapel code can be compiled to libraries to be callable from C, or Fortran or e.g. Python also supported. Chapel includes preliminary work to target NVidia GPUs. Chapel 2.0 is expected in the next six months. The current version 1.28 deprecates a lot of functions, and also syntax, the I/O-operator <~>.

Goals

Chapel aims to improve the programmability of

parallel computer Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different for ...

s in general and the Cascade system in particular, by providing a higher level of expression than current programming languages do and by improving the separation between algorithmic expression and

data structure In computer science, a data structure is a data organization, management, and storage format that is usually chosen for efficient access to data. More precisely, a data structure is a collection of data values, the relationships among them, a ...

implementation details. The language designers aspire for Chapel to bridge the gap between current HPC programming practitioners, who they describe as Fortran, C or C++ users writing

procedural code Procedural programming is a programming paradigm, derived from imperative programming, based on the concept of the ''procedure call''. Procedures (a type of routine or subroutine) simply contain a series of computational steps to be carried ...

using technologies like

OpenMP OpenMP (Open Multi-Processing) is an application programming interface (API) that supports multi-platform shared-memory multiprocessing programming in C, C++, and Fortran, on many platforms, instruction-set architectures and operating syste ...

and MPI on one side, and newly graduating computer programmers who tend to prefer Java, Python or Matlab with only some of them having experience with C++ or C. Chapel should offer the productivity advances offered by the latter suite of languages while not alienating the users of the first.

Features

Chapel supports a multithreaded parallel programming model at a high level by supporting abstractions for

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 ...

task parallelism Task parallelism (also known as function parallelism and control parallelism) is a form of parallelization of computer code across multiple processors in parallel computing environments. Task parallelism focuses on distributing tasks—concurrent ...

, and nested parallelism. It enables optimizations for the locality of data and computation in the program via abstractions for data distribution and data-driven placement of subcomputations. It allows for

code reuse In software development (and computer programming in general), code reuse, also called software reuse, is the use of existing software, or software knowledge, to build new software, following the reusability principles. Code reuse may be achiev ...

and generality through

object-oriented Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of pro ...

concepts and

generic programming Generic programming is a style of computer programming in which algorithms are written in terms of types ''to-be-specified-later'' that are then ''instantiated'' when needed for specific types provided as parameters. This approach, pioneered b ...

features. For instance, Chapel allows for the declaration of locales. While Chapel borrows concepts from many preceding languages, its parallel concepts are most closely based on ideas from

High Performance Fortran High Performance Fortran (HPF) is an extension of Fortran 90 with constructs that support parallel computing, published by the ''High Performance Fortran Forum'' (HPFF). The HPFF was convened and chaired by Ken Kennedy of Rice University. The fi ...

(HPF), ZPL, and the

Cray MTA The Cray MTA, formerly known as the Tera MTA, is a supercomputer architecture based on thousands of independent threads, fine-grain communication and synchronization between threads, and latency tolerance for irregular computations. Each MTA proce ...

's extensions to Fortran and C.

Notes

References

External links

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{{Numerical analysis software Cray Array programming languages C programming language family Concurrent programming languages Object-oriented programming languages Programming languages created in 2009 2009 software Free software projects

Goals

Features

See also

Notes

References

Further reading

External links