> Why do these guys not just build a lisp OS on top of some UNIX-system, so that every call to the OS goes through that layer? In Mezzano's case, presumably be

> Why do these guys not just build a lisp OS on top of some UNIX-system, so that every call to the OS goes through that layer? In Mezzano's case, presumably because they wanted to build an OS in Common Lisp, not on top of the C that a Unix system would be implemented in. Looking at their Patreon (https://www.patreon.com/froggey https://www.patreon.com/froggey) and FAQ (https://mezzanos.herokuapp.com/static/everyone/faq1.html https://mezzanos.herokuapp.com/static/everyone/faq1.html), part of the purpose of the OS is to re-explore the Lisp machines from the '80s. I know that if I built an OS, my purpose would likely be either learning, or experimentation with some concept that would be difficult to implement in any of the standard existing systems. Building on top of an existing base would defeat the point of the exercise, IMO.