Fortress: An Experimental High-Performance Programming Language
Fortress is a discontinued, experimental programming language designed primarily for high-performance computing. Created by Sun Microsystems with support from DARPA’s High Productivity Computing Systems (HPCS) project, Fortress aimed to address the growing need for improved software tools that could efficiently utilize advanced computer architectures, particularly in scientific computing and complex simulations. Although it has since been abandoned, Fortress remains a landmark project in the history of programming languages, offering insights into the development of modern language design and the pursuit of optimization in parallel computing.
The Origins of Fortress
The development of Fortress began in the early 2000s, under the leadership of Sun Microsystems and with the direct involvement of DARPA. The goal of the project was to create a language that could offer both high performance and high productivity for computational scientists working with large-scale problems. The project was particularly concerned with the challenges posed by emerging multi-core processors and parallel computing, which required new approaches to writing efficient and maintainable software.
One of the key figures in the design of Fortress was Guy L. Steele Jr., a prominent computer scientist known for his contributions to the development of programming languages such as Scheme, Common Lisp, and Java. Steele’s experience and expertise in language design played a pivotal role in shaping the overall vision of Fortress. His involvement ensured that the language was not only efficient but also capable of supporting high-level abstractions that made it more accessible to scientists and engineers.
Key Features and Design Philosophy
Fortress was built with several unique design principles in mind, reflecting its focus on performance and productivity. Among its distinguishing features, the following stand out:
1. High-Performance Computing Focus
The primary goal of Fortress was to enable high-performance computing on modern hardware. It was designed with an eye toward parallelism, which was essential given the multi-core processors that were becoming increasingly prevalent in supercomputers. To achieve this, the language included support for fine-grained parallelism, allowing developers to write code that could scale efficiently across multiple processors without the typical challenges of managing parallelism manually.
2. Modern Syntax and High-Level Abstractions
Fortress sought to improve upon the syntax of traditional scientific programming languages such as Fortran and C, while still maintaining compatibility with these languages. It provided high-level abstractions that allowed for more intuitive programming without sacrificing the performance benefits typically achieved through lower-level languages. This made Fortress an attractive option for scientific computing, where the ability to express complex algorithms concisely is a significant advantage.
The syntax of Fortress was designed to be both modern and readable, borrowing elements from other popular programming languages such as Lisp, Python, and Fortran. Its use of an infix notation for expressions and a powerful type system allowed for a balance between performance and readability, which was crucial for users involved in large-scale simulations and mathematical modeling.
3. Declarative Parallelism
One of the most notable features of Fortress was its approach to parallelism. The language provided declarative constructs that allowed developers to express parallelism without needing to manually manage threads or synchronization. This was intended to make it easier for programmers to harness the power of multi-core processors while avoiding the complexity and errors that often arise in manual parallel programming.
Fortress achieved this through the use of constructs like the forall keyword, which allowed for the parallel execution of loops and other iterative operations. This approach enabled programmers to write code that could be easily executed in parallel, without having to manually manage the distribution of tasks across different processors.
4. Strong Type System
Fortress introduced a sophisticated type system that was designed to catch many common programming errors at compile time. The type system was intended to provide guarantees about the safety and correctness of code, especially in the context of numerical computations and scientific modeling. This included support for both user-defined types and strong type inference, which helped reduce the chances of runtime errors and improved the reliability of programs.
5. Interoperability with Existing Languages
Although Fortress was a new language, it was designed with interoperability in mind. The goal was to allow developers to integrate Fortress code with legacy systems written in languages such as Fortran or C. This made it easier for users to gradually adopt Fortress without needing to rewrite entire codebases from scratch. The ability to call Fortran libraries directly from Fortress was one of the language’s key selling points for scientific computing.
Fortress and High-Performance Computing
High-performance computing (HPC) refers to the use of powerful processors, including supercomputers, to solve complex computational problems. In the early 2000s, HPC was increasingly dependent on parallel computing to meet the growing demands of scientific simulations, climate modeling, financial forecasting, and more. The shift toward parallelism introduced new challenges for programmers, as effectively utilizing multi-core processors often required deep knowledge of concurrency and low-level programming techniques.
Fortress aimed to make parallel programming more accessible by abstracting much of the complexity involved in parallel execution. This was an important development, as it allowed researchers and scientists to focus more on solving their domain-specific problems rather than on the intricacies of parallel execution. Additionally, the performance optimizations built into Fortress made it well-suited for computationally intensive tasks, ensuring that code could run efficiently on the most powerful hardware available at the time.
However, despite these innovations, Fortress faced significant challenges in the competitive landscape of high-performance computing languages. For example, languages like C++ and Fortran were already well-established in the HPC community and had extensive support for numerical computing. Additionally, the development of Fortress was somewhat hindered by the complex nature of the project and the difficulty of creating a new language that could outperform these established systems.
The Discontinuation of Fortress
Despite its ambitious goals, Fortress was discontinued in the early 2010s. Several factors contributed to this decision, including the rapid evolution of other programming languages and frameworks that addressed similar concerns. In particular, languages like C++ and Python, along with libraries such as NumPy and OpenMP, were able to provide many of the performance and parallelism benefits that Fortress aimed for, often with broader community support and more established ecosystems.
Another factor was the shift in the focus of DARPA’s HPCS project. As the field of high-performance computing advanced, there was an increasing emphasis on more flexible and general-purpose tools, rather than specialized languages like Fortress. The need for a new language specifically dedicated to HPC diminished as existing languages continued to evolve and improve.
Despite its discontinuation, Fortress remains a significant chapter in the history of programming language design. It was a bold attempt to push the boundaries of what was possible in high-performance computing, and its development provided valuable insights into the challenges and opportunities of parallel programming. Furthermore, many of the language’s features, such as declarative parallelism and strong type systems, continue to influence the development of modern programming languages.
Legacy and Influence
Although Fortress itself may no longer be actively used, its legacy lives on in various ways. Many of its ideas were ahead of their time and have since been adopted in other programming languages. The concept of declarative parallelism, in particular, has seen renewed interest in modern languages that aim to make parallel programming more accessible. For example, the use of high-level constructs for parallel execution has become a hallmark of languages like Julia and Rust, which are widely used in scientific computing and data science today.
The work done on Fortress also contributed to the broader movement towards high-performance computing languages that balance ease of use with raw performance. Researchers continue to explore new ways to improve the productivity and performance of programming languages in the context of modern multi-core and distributed systems.
Conclusion
Fortress was an ambitious attempt to create a programming language tailored to the needs of high-performance computing. Its design focused on parallelism, ease of use, and performance, making it an attractive option for computational scientists and engineers. While the project was eventually discontinued, the ideas behind Fortress remain influential in the field of programming language design. As the field of high-performance computing continues to evolve, the lessons learned from Fortress continue to shape the development of new tools and languages that seek to make computing more powerful and accessible.