I agree that this is initially confusion, but I think that if you spend more than a couple of days with Clojure you will understand the ubiquitous and liberal use of binding forms.
On Sun, Feb 22, 2009 at 2:42 PM, Mark Volkmann <r.mark.volkm...@gmail.com>wrote: > > On Sun, Feb 22, 2009 at 1:34 PM, David Nolen <dnolen.li...@gmail.com> > wrote: > > In general, I find that multiple arguments types for a function > confusing. > > If dotimes is going to take multiple types it should be a multifn. That > > seems to imply a performance hit. > > I think Clojure wisely does not (or rarely does not?) allow for multiple > > types to be passed into a function. > > On top of that it's trivial to produce a macro on top of dotimes that > does > > what you want that doesn't spend time checking the type of it's argument. > > Really my main goal is to make Clojure code as easy to read as > possible. In this particular case, I think code like this: > > (dotimes [n 3] (println "knock")) > > leaves the reader wondering "What is the n for?". > > Someone suggested this: > > (dotimes [_ 3] (println "knock")) > > That still seems like too much to read for what I'm getting. > > OTOH, (dotimes 3 (println "knock")) isn't likely to confuse anybody. > > Sure, I could get what I want by writing my own macro. The problem I > have with that is that I don't want to litter my code with calls to > custom macros that readers of my code have to figure out. I prefer to > use functions that readers will already be familiar with unless > introducing my own macros is going to significantly shorten the code. > > > On Sat, Feb 21, 2009 at 11:10 PM, Mark Volkmann < > r.mark.volkm...@gmail.com> > > wrote: > >> > >> On Sat, Feb 21, 2009 at 8:53 PM, André Thieme > >> <splendidl...@googlemail.com> wrote: > >> > > >> > On 21 Feb., 18:24, Mark Volkmann <r.mark.volkm...@gmail.com> wrote: > >> >> Currently the dotimes macro requires its first argument to be a > vector > >> >> for binding a variable to the number of times the body should be > >> >> executed. Inside the body, that variable is bound to the values from > 0 > >> >> to that number minus 1. How about changing this macro to also accept > >> >> an integer as the first argument instead of a binding vector for > cases > >> >> where the number isn't needed in the body. > >> > > >> > I don't find this very interesting. > >> > There several variants of how dotimes could be, but the one that we > >> > currently have is the one that is used since a few decades in Lisp, > >> > and it is the one that makes very much sense. > >> > > >> >> For example, > >> >> > >> >> (print "Santa says") > >> >> (dotimes 3 (print "Ho")) > >> >> (.flush *out*) > >> > > >> > (print "Santa saysHoHoHo") > >> > > >> > How often do you really want to repeat the same side effect many times > >> > in a row? > >> > Why does it hurt to just say (dotimes [i 100] ...)? > >> > This will not reduce readability dramatically, but is a consistant > >> > use of dotimes. It also does not reduce productivity. > >> > Why make a breaking change for this? > >> > >> Why do you say it would be a breaking change? I just got the following > >> to work with minimal changes to the dotimes macro. > >> > >> (dotimes 3 (println "Ho")) > >> (dotimes [n 4] (println n)) > >> > >> So both forms work with a single macro definition. > >> > >> Here's what I did. > >> > >> 1) Wrap the body of the macro inside the following: > >> > >> (let [new-bindings (if (integer? bindings) ['n bindings] bindings)] > >> ... > >> ) > >> > >> This creates the required binding when only an integer is passed and > >> using the supplied value for bindings otherwise. > >> > >> 2) Change every occurrence of "bindings" in the body to "new-bindings". > >> > >> 3) Move the (defmacro dotimes ... ) to just before (defn make-array > ...). > >> That's the first time it's used in core.clj and it will not be > >> after the definition of "integer?". > >> > >> Is there a reason to not make this change? > > -- > R. Mark Volkmann > Object Computing, Inc. > > > > --~--~---------~--~----~------------~-------~--~----~ 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 clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
