There are a huge number of programming languages to choose from, but only a few are described as system programming languages. If we could have anything we want from a new system language, what would it be?I recently announced the first Alpha release of the Heron programming language 1.0 on Artima.com. I talked a bit about the evolution of the language design over the course of the last five years. Some people who remembered the language from back when, commented on how they were a bit sad to see it become less of a systems language and more of an enterprise type language.

I think that the Heron feature set would permit it be used as a system language, but it would require this to be clearly demonstrated. I am thinking that the next steps for Heron are going to be implement a Heron to C or C++ compiler. This might be a good way to prove the viability of Heron with all of its fancy-pants features being used a system language.

The term "system programming language" is not super well-defined. Most of us "know it if we see it". Some programming languages that I consider to be system languages are: C, C++, Modula-2, Oberon, Fortran, D, Forth (am I missing any?). My rather unscientific criteria for a system language is: can you write an OS with it, without having to heavily rely on a foreign function interface (FFI) to C?

So I asked Nemanja and Achilleas on the Artima discussion forum of Heron what they would look for in a system language, and here is my take on their wish-list combined with my own:

Must have features

• compilation to native platform binaries
• tight control over resource management (e.g. optional garbage collection)
• compile time code execution
• typed memory management
• direct access to system resources
• efficiency both in CPU and memory consumption.
• no hard dependency on a runtime (e.g. VM or library)
• all high-level abstractions strictly follow "pay only for what you use" policy (e.g. polymorphism, closures, RTTI)
• deterministic resource deallocation
• a very static ang strong type system that would catch as many errors as compile time as possible

Nice to have features

• type deduction
• full support for functional programming
• simple FFI to C
• full support for dangerous actions like pointer arithmetic, but *not* defaults.
• a context-free grammar
• side-effect detection and enforcement
• explicit signature-based polymorphism
• A rich set of standard libraries that can be optionally linked if needed.
• A choice of static and dynamic linking should be provided

I found this to be an insightful wish list of features. It is definitely helping to guide my thinking about some features of Heron. What features would you expect from a modern system language?What features would you expect from a modern system language?