> writing one OS in Lisp seems like a fairly unrealistic, slightly weird dream.
It's not - it actually was done[1]. There were OSes written in other high-level languages, like Smalltalk and Forth (which may not be "high-level", but at least it's higher level than C).
I'm not sure I'd classify Forth as higher level than C; in many ways, it operates on abstractions more akin to assembler. In every way, it's really, really strange.
Agreed. Typeless, completely unsafe, treats RAM as a contiguous byte array with a dictionary growing one way and data stack growing the other, allows using the return stack as scratch space... it's very asm-ish.
It is a very good way of managing complexity, though, at the level you would write a program in assembly. And higher-level stack languages (such as Factor) bring that same degree of complexity management to application-land.
It's not - it actually was done[1]. There were OSes written in other high-level languages, like Smalltalk and Forth (which may not be "high-level", but at least it's higher level than C).
[1] http://en.wikipedia.org/wiki/Lisp_machine