Regarding #2: I have a complete version of McCarthy's original evaluator at https://programmingpraxis.com/2011/11/01/rip-john-mccarthy/ https://programmingpraxi

Regarding #2: I have a complete version of McCarthy's original evaluator at https://programmingpraxis.com/2011/11/01/rip-john-mccarthy/ https://programmingpraxis.com/2011/11/01/rip-john-mccarthy/, and it doesn't use a single mutation.