and i dont like how it's inconsistent that echo is not using the $ syntax (which makes sense internally, as it's a built-in, rather than executing the $echo command).

Overall, it is cute and neat, but i find that if you are looking to write bash scripts that require this level of programming, you'd be better off writing it in python, or perl. Only in very austere environments can this be utilized, but the requirement of having `bc` installed means you must also have the ability to run package installation, so might as well run the package installation for a full on programming language!