Rather than just a critique, I'm curious where and how you use it with what benefits it brings you? I could certainly see it in UI or untrusted parts. Maybe also during development in a way that auto-generates C or something that runs in production.
To be perfectly fair, on the decision matrix Tcl gets a helpful boost due to my own familiarity with it and playing nice with C; if a butterfly had flapped it's wings just a little bit differently or I was starting out today I would probably be using something else. Probably Java. Ada would be great, but the lack of ecosystem diversity makes me apprehensive.
So, there you have it: REBOL, RED, and Nim. Maybe Ivory language from Galois, too, but you need to know Haskell for that.
Don't have any experience with Nim, but I share your interest for the same reasons. Haskell and I don't get along, maybe I'm too old and set in my ways?
Did you catch the link to/discussion of Little shared on here a few days ago? It might be of interest. https://news.ycombinator.com/item?id=11530097
I'd say it's not a good language to go with today for same reasons I'd say Tcl isn't. It's an interesting improvement especially to get better syntax with legacy compatibility with field-proven, TCL modules. And TK is still the shit for portable, easy-to-build GUI's. A TCL shop should definitely experiment with it and maybe incrementally upgrade their code. I think I'd be fine with a more typed, efficient, and fixed version of Tcl for some apps. Especially a command shell replacement or prototyping system.
Just not production unless it's non-critical like what you use it for. I don't even use it to glue to critical things as the glue is part of the TCB to a degree. Gotta find close-to-metal, abstract, typed, efficient, and macro'd stuff to replace it. At least we have contenders.
I don't personally know of anyone in medical using it, but your comment about no OS does prod me to say that I have wondered if running Forth on bare metal for medical is viable and/or desirable on a greenfield project. I'm not saying I would do it, but I would happily cheer on someone else. (OP, don't do this, I'm delusional)
And OP, I really hope that my wall of text won't be discouraging in any way. Personally, I found that documentation is (a la Homer Simpson) the cause of, and solution to, all of life's problems in a regulated environment. If you master that, document honestly and eagerly, it's downhill from there and life will be good.