'when pred' just checks that you're not passing in garbage for the predicate -- it's probably not really necessary and it might be better to let Clojure throw an exception.
Totally agree on your point with the branching. That's not really FP- related, it's only that most FP languages allow pattern matching and prefer to be "lean" by handling special cases for you. On Feb 1, 9:53 pm, ka <sancha...@gmail.com> wrote: > Hi clojure folk, > > I'm reading up on clojure from the book 'Programming clojure'. In > chapter 2 there is a statement - > > "The imperative indexOfAny must deal with several special cases: > null or empty strings, a null or empty set of search characters, > and the absence of a match. These special cases add branches > and exits to the method. With a functional approach, most of these > kinds of special cases just work without any explicit code." > > I'm not quite sure if I understand this properly. How is it that with > a functional approach, most of these special cases like null checks or > empty checks get handled automatically? I mean isn't that a property > of the language / api rather than the programming approach per se? > Please explain with some examples! > > On a similar note, following is the definition of the function index- > filter given in the book :- > > (defn index-filter [pred coll] > (when pred > (for [[idx elt] (indexed coll) :when (pred elt)] idx))) > > Why is the 'when pred' check necessary? > > Thanks! -- 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
