I was reading about system programming when I came across the semantic gap and how we have to bridge that for better software development.
Then the term programming language domain came in which apparently bridges the semantic gap but getting in the specification and execution gap. Can someone explain this to me with an example maybe?
When working in a particular application domain you think in concepts of that domain. For example, if you are developing software for lawyers you will work and think in concepts such as: bill, statute, law, paragraph etc.
Execution platform, on the other hand, is where the software eventually run (a physical or virtual machine). In that domain you have entirely different concepts: stack, registers, instructions etc.
Someone, or something must translate a model of a solution from application domain to the execution domain. The semantics gap is huge. General-purpose languages (GPLs) alleviate the problem by using a higher level abstractions that are easier to work with (e.g. classes, objects, methods, functions, parameters, collections). So instead of translating the solution directly to the machine, you translate it manually to the programming language, bridging the specification gap, and the compiler mechanically do the translation to the target machine (or many different machines) bridging the execution gap. Still a lot of manual work in translating concepts from the application domain to GPL.
Domain-specific languages (DSL) go a step further. They are based on concepts found in the application domain. Thus, the specification of the solution in DSL should be easy 1:1 mapping. There is no gap between the application domain and the specification. The DSL specification is now translated (usually in multiple steps, e.g. DSL->GPL->machine code) to the target execution platform mechanically.
For further reading on the topic of bridging the semantic gap, I suggest papers on Language-Oriented Programming topic by Martin Ward and Sergey Dmitriev. To read more on DSLs in general I suggest a book "DSL Engineering: Designing, Implementing and Using Domain-Specific Languages" by Markus Voelter.
