There have been a number of unrelated discussions regarding recursion on this list. I believe that recursion occurs in a wider spread of areas than is usually recognised.
Heres a list of some such areas. Please note I am using recursion in a broad and somewhat fuzzy sense. Narrow specific definitions would lead to conclusions like: -- Prolog has no functions or procedures so it has no recursion -- Since recursion is equivalent to stack + iteration therefore Fortran supports recursion. Heres (an initial approx to) such a list: ------------------------------------------------------- recursive functions recursive data -- eg linked lists, trees nesting self reference -- Y combinator well founded induction structural induction bootstrapping language to describe language -- syntax - yacc in yacc language to describe language -- semantics - lisp in lisp -- metacircularity Goedel's theorem <- meta-mathematics <- ordinary math undecidability <- universal TM <- Turing machine as ordinary computer reentrancy [An OS-like program fails to be reentrant for the same reason that Fortan-like language fails to support recursion -- Non use of stack] virtualization in OS Introspection in modern languages Models to metamodels corecursion - laziness, infinite datastructures - semantics of generators/iterators in python Von Neuman machine - code is data -- therefore quondam hardware becomes software - data can be code -- viruses -- http://mail.python.org/mailman/listinfo/python-list
