Mike, I mean this is just one example to prove your ideas, not to disprove.
On Oct 29, 4:26 am, Mike Meyer <mwm-keyword-googlegroups. 620...@mired.org> wrote: > On Thu, 28 Oct 2010 18:12:39 -0700 (PDT) > > andrei <andrei.zhabin...@gmail.com> wrote: > > > I'll try to extend Mike's answer by one more example. Consider `and` > > Lisp macro. It is not a function, because it must evaluate it's > > arguments lazily, and using macros is the only way to do it. > > Actually, this is the first case, and a classic example of it: you > need to control how many times the arguments are evaluated. > > > But try > > to apply `and` to the list of values (I know, that it's a job for a > > function `every?`, but how will you implement this function itself?): > > > (apply and (list true true false true)) ==> error > > And this is the issue of not being able to pass macros to higher order > functions. > > > You cannot do it, since and is not a function. So, you need to use > > wrapper around `and`: > > > (reduce #(and %1 %2) (list true true false true)) ==> false > > > And this is still not the perfect solution, since it is not lazy. > > > So you can see both advantages and disadvantages of using macros. > > Which is why you only want to use them when you have to. If you don't > need the advantages, why put up with the disadvantages? > > <mike > -- > Mike Meyer <m...@mired.org> http://www.mired.org/consulting.html > Independent Network/Unix/Perforce consultant, email for more information. > > O< ascii ribbon campaign - stop html mail -www.asciiribbon.org -- 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 Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
