Please take a moment to pause and consider what you're writing. Someone here wrote "let the backend generate correct code". I responded that people usually write shell programs, not backends.
You wrote that you know of no backends--- but we have a long history of macro preprocessing/expansion of shell scripts.
M4 would excel at this adaptation...
Which isn't even necessary, because everything posix conformant has "set -e". And if "posix" isn't good enough, the Bourne Shell back to 1978 has it (probably earlier).
Autotools is written in M4.. M3/M4 were developed by K&R to help automate generating mostly shell programs. In 1974-1977.
For someone who purports to be so oldschool, you're sure missing a lot.