Sun has open-sourced the preliminary compiler for its high-performance programming language project, Fortress.

The compiler, released by Sun this week on its Fortress website, is the latest piece of the language to see the light of day, and open sourcing it is an effort to get developers interested.

Fortress is still at an early stage, and Sun said it is aiming to get feedback from programmers in government, academia and industry. While Fortress is a general-purpose language, it has features that Sun says makes it particularly suitable for high-performance computing (HPC), so Sun is focusing on that group as an initial base for the project. Open source is another way of drawing attention from developers with particular interests, Sun said.

The language is one of three developed as part of a US Department of Defense programme - DARPA's HPCS programme - along with IBM's X10 and Cray's Chapel.

Sun intends the language as a successor to Fortran, still used for many high-performance applications. It is intended to offer far more programmability than existing languages - the ability to address the numerous processors and cores available in HPC projects and modern multicore computer chips.

For instance, it supports implicit parallel computation, meaning it assumes all the work carried out will be split into workloads to be carried out in parallel on different processor resources. Most languages require parallel computation to be explicitly requested.

The language is designed from scratch from the ground up, allowing it to be completely tailored to HPC programming, Sun said: "We aren't tying our hands behind our back by attempting to support legacy and obsolete language features," Sun said in explanatory notes accompanying Fortress.

While that may mean a steeper learning curve for developers, the company is hoping to get developers on board by letting them work in mathematical notation. "It allows programmers to reason in their problem domain without translating entities such as quantities and physical units into unfamiliar abstractions," the company said on the Fortress site.

So far Sun has released a series of draft specifications for the language and formal calculi and soundness proofs for several features, and has demonstrated parallel Fortress execution.

The initial effort targets the Java Virtual Machine, allowing it to run on a large number of platforms, but the intent is for Fortress to run directly on supercomputers with large stores of addressable memory, clusters of commodity hardware, workstations and other common HPC set-ups.