On Sat, Dec 15, 2012 at 3:58 PM, Peter West <peter.b.w...@gmail.com> wrote:
> But it can't, can it? In this context (apply f [i]) with respect to (f i)* > apply *has *side-effects*! > This doesn't really make any sense. There are no side effects here. I think maybe you just don't understand what apply does. Let me try to explain it a different way. Some functions, like +, are designed to take 1, 2, 3, 4, 5, or any number of arguments. You can write: (+ 1 2) (+ 1 2 3) (+ 1 2 3 4) (+ 1 2 3 4 5) etc. The "contract" for + is that it takes any number of numbers as an input. One thing + can't do is add up the numbers in a list, at least not when written in this way: (+ [1 2 3 4 5]) This doesn't make any sense, because + is expecting numbers, and we passed it a vector. It might seem somewhat ironic that + can't take a list of numbers. Obviously, it knows how to add a series of numbers, it just expects them to be one after each other, as arguments, not all bundled up in a list. If only we could delete those brackets around [1 2 3 4 5]... If only we had some sort of "adapter" that could take a list/vector of items, and pass them in as multiple arguments to a function that was designed to take multiple arguments... That is what apply does. (apply + [1 2 3 4 5]) turns into (+ 1 2 3 4 5) Similarly, (apply str [\a \b \c \d]) turns into (str \a \b \c \d) -- 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
