Is there a short explicit construction of an universal recursive function? All definitions I have seen involve numbering of Turing machines in some way, which is possible yet seems hard and unmanageable to write in a higher-level programming language (like Python, Haskell etc.)
Writing universal recursive function
lo.logic;computability;pl.programming languages
How about McCarthy's original Lisp interpreter (originally here)? It's universal, works on a natural encoding (a Lisp AST), doesn't rely on an external interpreter, and is about 20 lines.