I agree with Laurent's idea that you should pull this out as a
separate function, but I think the most direct answer to your question
is that you can bind the map entries in a destructuring as if they
were two-element vectors.
(map (fn [[ingr quant]] (* (cost ingr) quant)) (cookbook drink))
Joe
On Jul 28, 8:02 pm, Daniel Glauser <danglau...@gmail.com> wrote:
> Hello folks,
>
> I'm working on some sample code and I have a feeling that there is an
> easier/more succinct way to code this. Any help or RTFM with a link
> is appreciated.
>
> Given:
>
> (def cookbook {:Coffee {:coffee 3, :sugar 1, :cream 1},
> :Decaf-Coffee {:decaf 3, :sugar 1, :cream 1},
> :Caffe-Late {:espresso 2, :steamed-milk 1},
> :Caffe-Americano {:espresso 3},
> :Caffe-Moca {:espresso 1, :coco 1, :steamed-milk
> 1, :cream 1},
> :Cappuccino {:espresso 2, :steamed-milk 1, :foamed-milk
> 1} })
>
> (def cost {:coffee 0.75,
> :decaf 0.75,
> :sugar 0.25,
> :cream 0.25,
> :steamed-milk 0.35,
> :foamed-milk 0.35,
> :espresso 1.00,
> :cocoa 0.90,
> :whipped-cream 1.00 })
>
> (def menu {:Coffee 1,
> :Decaf-Coffee 2,
> :Caffe-Late 3,
> :Caffe-Americano 4,
> :Caffe-Moca 5,
> :Cappuccino 6 })
>
> I'm trying to write a function to print out the menu listing the cost
> of each drink. It works (sort of) but I keep thinking there is an
> easier way.
>
> (defn print-menu [menu]
> (do
> (println "Menu:")
> (doseq [[drink number] menu]
> (println (str number ", " (drink-name drink) ", "
> (reduce +
> (map (fn [map-entry] (* (cost (key map-entry)
> (val map-
> entry)))) (cookbook drink))))))))
>
> Specifically this part:
> (map (fn [map-entry] (* (cost (key map-entry) (val map-entry))))
> (cookbook drink))
>
> Is there a way I can get at the map key and value using destructuring
> without knowing what the key is ahead of time?
>
> Thanks,
> Daniel
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