I concur with Timothy's assessment. Really well stated and illustrated use
of reduce with a named reduce function.
On Fri, May 3, 2013 at 10:52 PM, Timothy Baldridge <tbaldri...@gmail.com>wrote:
> In general, loop/recur shouldn't be considered idiomatic, IMO. Instead,
> try for a more functional style:
>
>
> due = 100
> cards = cards.map do |card|
> card.applied_balance = max(0, due - card.balance)
> due -= card.applied_balance
>
> becomes (untested):
>
> (defn apply-balance-1 [{:keys [due] :as accum} [card-id balance]]
> (let [applied (max (- due balance))]
> (-> accum
> (assoc-in [:applied card-id] applied)
> (assoc-in [:due] due))))
>
>
> (reduce apply-balance-1
> {:due 100}
> {:card-id-1 4404.00
> :card-id-2 3020.00
> ....etc....})
>
> Often I have found that using reduce forces me to break functions into
> several parts. If I used loop/recur, normally the function prelude,
> postlude and loop block are all smashed into a single function. With reduce
> + a do-step-1 function (as seen above) we can more easily reason about what
> is happening. The code is then easier to test as well, as we can test the
> calculations apart from the loop logic.
>
> When I'm performing Clojure code reviews, I often consider loop/recur to
> be a code smell.
>
> Timothy
>
>
>
> On Fri, May 3, 2013 at 3:53 PM, Armando Blancas <abm221...@gmail.com>wrote:
>
>> On Friday, May 3, 2013 1:15:24 PM UTC-7, Robert Pitts wrote:
>>>
>>> Armando was a good citizen and sent along a plain-text version as well –
>>> https://groups.google.com/**group/clojure/msg/**
>>> 6aae8287bc55d436?dmode=source&**output=gplain&noredirect<https://groups.google.com/group/clojure/msg/6aae8287bc55d436?dmode=source&output=gplain&noredirect>
>>
>>
>> That must have been Google Groups doing the right thing... nice feature.
>>
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>
>
>
> --
> “One of the main causes of the fall of the Roman Empire was that–lacking
> zero–they had no way to indicate successful termination of their C
> programs.”
> (Robert Firth)
>
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