I've been on this horse for a while now. I've settled on learning Ada/SPARK. Ada 2022 will start feeding a new SPARK 2014 update. Yes, they are both verbose, if you don't like that sort of thing, and don't like Pascal-like syntax. Believe me, I like APL/J/k/uiua/BQN and Forth and ASM. I am usually syntax agnostic as long as the PL and the ecosystem (more important than most think), meet your needs. I tried Rust back in 2018, and then again in 2023, but found it very complex and Ok, not a fan of the syntax. I would have preferred more ML or Haskell-like syntax. Zig seemed nice, but different use case, and too new. After all, Ada/SPARK have been on huge, high-assurance, high-safety applications for decades. Rust is getting some of their love, and vice versa. AdaCore had created a verified Rust compiler, but with a real world product (Blacktail hoist) in the works, we need a toolset and guarantees and ease of auditing and acceptance to achieve high safety and standards certifications. Think aerospace, defense, railway, and automotive. I started programming in 1977, so there's always a place in my heart for ASM/C. I played with F#, F*, and LOW from MS, and they are good, but they and Rust simply don't have the real world legacy of Ada/SPARK. I have been using Shen to write some formally verified models of less safety-critical areas of our software and I find it refreshing, however, my day job is to stay focused on Ada/SPARK until Rust matures more with a formally verifed proven toolset. There are certainly efforts and crates available in that direction, so hopefully others will bring it to where it needs to be. Lean is another one I have been playing with for some of the more overall logic proof of the system we are building.