Lisp (and Scheme) allows you to express complex systems and problem domains in more simple terms than any other language can. For all its brilliance, Haskell resists most of the attempts people make to just hack and write useful code quickly.

Researching early Unix and low-level systems, and I ended up spending a good amount of time with this: the actual source of the first C compiler, written by Dennis Ritchie in 1972. Everything we write today traces back to this. Worth reading if you haven't... source: https://github.com/jserv/unix-v1/tree/master/src/c

Accessible via the `complex.h` header What other useless things have you encountered in C?