It is pretty straight-forward. However, Modula-2 and Pascal's are even more so as you can represent everything with a simple BNF grammar. There's more consistency, less corner cases, and so on. Every change they make is specifically designed to improve it while maintaining simplicity. The most complicated and modern one can be described fully in around 30 pages [1]. The uppercase and declarations throw people sometimes but keep in mind people used text editors w/out syntax highlighting.
http://www.oberon.ch/pdf/CP-Lang.pdf
re mutually exclusive. Nah, there's still tradeoffs you can make. Cyclone and Rust both do that with better design decisions to allow safe, manual management. At some point, you have to choose one or the other though. Your language design matters at this point where the compiler has to know it can remove a check. C's design is so rough and allows so much unpredictable behavior that this is an ongoing research problem for it. Whereas, it happened with Modula-3 libraries in one academic project and happened for Ada with SPARK.
Re Modula. Oh yeah, it's not updated anymore. I was just illustrating a language as lean and efficient as C that was safer & easier to compile. A better foundation. It was rejected by C users when it did have compilers. Plus, there's a Modula-2 to C compiler floating around the net.
Re Free Pascal and Lazaurus. Interesting feedback. I'll look into that to see if I or developers could remedy it. Except for Emacs: Lazarus is the IDE and better suited. Emacs support might stay dead. Re D. Yes, it's more like C++ but can be used where C is many times. I see you're looking for simple stuff, though. Re Cyclone. It's not simple but not hard either. Remember C is deceptively simple: using it safey is HARD. Cyclone is slightly more complex but way easier to use. Unmaintained, yes, but people (esp GCC or LLVM types) could pick it up any day... if they weren't glued to C. Good call on the Rust connection.
https://doc.rust-lang.org/reference.html#appendix-influences
re Julia. That's not good... re Ocaml. I think you're focusing too much on complexity of semantics vs complexity of effective use. It's worthwhile to increase learning curve a bit to boost productivity, safety, and maintenance. re Haskell. That reaction surprised me and you're the first to call it simple. Ive been holding off cuz it seemed ridiculously hard and different. What did you use to learn it? Btw, I agree fast Haskell is usually ugly but look up Tolmach's Habit programming language. It's on hold right now cuz he had a better project.