oke, So map is taking the first item of coll and put's it in x. Then it calling second-item . Now I understand .
Thanks a lot for the patience and explanation. Roelof Op vrijdag 24 oktober 2014 16:01:48 UTC+2 schreef Laurens Van Houtven: > (defn double [x] (* x 2)) > > See, x is right there ^ > > Now, I do (double 10). How does Clojure “know what the x is”? There’s no x > in that expression. > > Exactly the same with map. The x is just a name; it doesn’t matter what it > is. The only thing that matters is that you call that function (whether > it’s double or second-item or whatever) with a single argument. In (double > 10), I’m calling it with 10. In (map second-item coll), map is calling > second-item with each of the items in coll. These are exactly the same > thing: in both cases it’s just function application. > > hth > lvh > > > On 24 Oct 2014, at 15:56, Roelof Wobben <rwo...@hotmail.com <javascript:>> > wrote: > > > Sorry but I still do not have a clue how clojure knows what x is. > > > > the first part where x is mentioned is the fn part and on the map part > there is no mention about x. > > > > Roelof > > > > > > Op vrijdag 24 oktober 2014 15:51:30 UTC+2 schreef Laurens Van Houtven: > > Hi Roelof, > > > > > I understand that part. > > > > > > so we have (map second-item collection) where second-item and > collection are arguments of map. > > > > Yep. > > > > > Then we have second-item ( fn [x] (get x 2) > > > which can be read as : > > > > > > ( second-item [x] (get x 2) . > > > > This makes no sense to me. second-item is a fn. In this syntax, > (malformed because of a missing closing bracket), you are calling > second-item with [x] and (get x 2), without having defined x. > > > > > in the map there is only ( map second-item collection) > > > > > > or is the collection a argument of second-item and a argument of map. > > > > No. second-item and collections are the arguments of map. map will call > second-item for each element in coll. map’s job is to “pull apart” the > collection, element by element, pass it to f, and give you the result back. > > > > hth > > lvh > > > > -- > > You received this message because you are subscribed to the Google > > Groups "Clojure" group. > > To post to this group, send email to clo...@googlegroups.com > <javascript:> > > Note that posts from new members are moderated - please be patient with > your first post. > > To unsubscribe from this group, send email to > > clojure+u...@googlegroups.com <javascript:> > > For more options, visit this group at > > http://groups.google.com/group/clojure?hl=en > > --- > > You received this message because you are subscribed to the Google > Groups "Clojure" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to clojure+u...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > > -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
