On 27 nov, 18:09, Rich Hickey <[EMAIL PROTECTED]> wrote: > > > (defn trampoline [f] > > > (let [ret (f)] > > > (cond f > > > (fn? ret) (recur ret) > > > (instance? org.clojure.lang.NoBoingWrapper f) (.returnInstance > > > f) > > > else ret))) > I considered that, and it's still a possibility, but I don't want > people thinking they need to call (trampoline-return x) all the time. > The only time you need to wrap the return value is when the result is > an actual fn.
Well, actually the above implementation allows to not use (trampoline- return) for all common cases, and would just be a standard work-around in the fn-as-value returning case. Isn't it more a matter of where to put the focus on the documentation. Let's try a modified version of trampoline doc with (trampoline- return) explanation added : " trampoline can be used to convert algorithms requiring mutual recursion without stack consumption. Calls f with supplied args, if any. If f returns a fn, calls that fn with no arguments, and continues to repeat, until the return value is not a fn, then returns that non-fn value. Note that if you want to return a fn as a final value, wrap it in a call to trampoline-return (or wrap your fn in some data structure of your own, and unpack it manually after trampoline returns). " > But it is nice to do the unwrapping in trampoline itself. Yes, there is just one special case, why not provide a standard way to handle it ? > My thinking is that such mutually-recursive state machines are > designed of-a-piece, so any wrapping protocol would be local, and I > wanted to minimize the amount of cruft one would have to add to use a > trampoline. > > Rich --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
