I wrote this macro a while ago that allows you to do this in a relatively clean way:
http://paste.lisp.org/display/81703 Example usage: => (let-map [a 5 b (+ a 12)]) {:a 5, :b 17} - Chas On Dec 9, 2009, at 1:20 PM, bOR_ wrote: > Hi all, > > I want to make a hash-map where the value of one key depends on the > values of other keys in the hash-map. Is there a way to do this, > without needing an external reference to the hash-map? > > {:a 1 :b 2 :c #(+ :a :b)} > > Similarly, when filling a struct, I often want to refer to the bits I > already have filled in. I solve that now by just embedding the (struct > mything.. in a let, and just use the serial nature of let to calculate > for example c from a and b. Is there a way that while filling a struct > I can refer to it? > > I would like to do this > > (defstruct virus :epitopes :mutations :viral_load) > (def myvirus (struct virus 3 5 (+ (* 0.1 :epitopes) (* > 0.2 :mutations)))) > > Instead of > > (defstruct virus :epitopes :mutations :viral_load) > (let [epitopes 3 > mutations 5 > viral_load (+ (* 0.1 epitopes) (* 0.2 mutations))] > (def myvirus (struct virus epitopes mutations viral_load)) > > As you can see there is some room for being more concise and compact > if you can refer to keys in the same hash-map or struct, even if the > hash-map / struct is still being constructed. > > -- > 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 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
