Oh I had a very interesting class in eng. school about programming languages paradigms. About subtle differences between different implementations of the same concept. Ada, C++, Java, C# (could've gone to functional languages but the lesson was painful enough with these 4). Type-erasure, explicit/implicit/partial template instantiation, visibility rules. And then design patterns, in all those languages. How a singleton makes no sense in a language that's not 'full' object and has 'packages' (not the java ones), how GC/RAII/controlled-types change the patterns. It was both a course on 'using language concepts correctly, picking them carefully for a specific need and not 'to avoid writing 3 more lines of code' and also a lesson in 'how can you paint yourself in a corner and prevent yourself from handling the simplest of requirements change'...

Very interesting to see how our mind is shaped by the tools we use.