you can basically make things as reliable as you by having lot of machines. - Joe Armstrong

We could of course redefine compose to a version of compose that work with debugging with debugging things. That would be horrible. That would mean we would need to compose pure functions. We would need to compose functions for debugging and everything on the planet.

I think we seem to have forgotten that things can be small. This way of decomposing systems into small things that I can reason about.

Sometimes changing one line of legacy code is incredibly difficult than totally rewriting the entire stuff.