There are a lot of features of bash that are probably fundamentally incompatible with this, but for non-interactive scripts I really only want to use languages

There are a lot of features of bash that are probably fundamentally incompatible with this, but for non-interactive scripts I really only want to use languages that read in the entire file and parse it before executing a single line. This can even allow stuff like JIT compilation which, though it does bear some startup cost is faster in the long run.