I'm not entirely sure what issue you are trying to raise here, so I will guess:
In languages which support tail recursive optimizations for recursive functions, those optimizations can still be deployed if the function in question contains an expression which uses some different recursive function. Why should J's induction be any different? Thanks, -- Raul On Mon, Jan 8, 2018 at 7:08 PM, Jose Mario Quintana <[email protected]> wrote: > The claim [2], as written, does not impose any restrictions on FN or FT > apart from being monadic; thus, F itself could be embedded in FB and could > provide an opportunity to cheat and defeat its purpose. > > Surely you mean something more substantial. Can you elaborate your claim? > > > On Wed, Jan 3, 2018 at 8:09 AM, Raul Miller <[email protected]> wrote: > >> [1] >> >> If I have a tail recursive function F, which calls function G, there >> is normally no problem with G signaling that F needs to exit. Just >> return a distinguished value from G and in F have an if statement >> which returns when that happens. Since F is tail recursive, nothing >> more needs done. >> >> So I would like to see an example of how this description: >> >> >> I have a deeply embedded function that discovers that it has completed >> the >> >> task set before it. ... >> >> >> >> This function was not part of the initial design. >> >> has anything to do with tail recursion. >> >> [2] >> >> If I have a recursive verb (F y) implemented in J, which satisfies the >> constraints for tail recursion, I believe that there is always a pair >> of companion functions (FB y) (FT y) such that an F workalike can be >> written: >> >> F=: FB^:FT^:_ y >> >> which satisfies the "bounded stack usage" guarantee of tail recursion. >> And this form has an additional advantage, which is that a rewrite >> which removes the bounded stack character requires work on the part of >> the developer which is quite significant - it's unlikely that you will >> have someone making such changes without realizing that they are doing >> so. >> >> But I would be interested in seeing a counter-example that destroys my >> belief, if counter examples exist. >> >> Thanks, >> >> -- >> Raul >> >> >> On Wed, Jan 3, 2018 at 5:44 AM, Erling Hellenäs >> <[email protected]> wrote: >> > Try to remove all references to persons from your postings. >> > >> > I don't think my post is in any way strange. According to my judgement no >> > further explanation is needed. >> > >> > /Erling >> > >> > >> > Den 2018-01-02 kl. 13:18, skrev Raul Miller: >> >> >> >> If you would answer those two questions we could do that. >> >> >> >> Thanks, >> >> >> > >> > ---------------------------------------------------------------------- >> > For information about J forums see http://www.jsoftware.com/forums.htm >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
