In one of those "could have been" moments, back in c.1994 I wrote a simple web browser which used SafeTcl (a sandboxed Tcl) to render. I got a few things wrong in hindsight - there was no static markup at all, the whole page was rendered by Tcl although there was a simple Tcl function to render blocks of text and TeX-like markup in Tcl strings.

Tcl is more pleasant than Javascript, but still has some horrible parts like poor support for structs, nothing really equivalent to a pointer, clumsy escaping, and (at the time) no support for dynamically linked extensions.