Hey Olivier,
You can shorten the body of your function with nil-punning and in lining
next-time (rather than explicitly letting it), e.g:
(if (empty? events)
timed-events
(let [current (first events)
next-time (+ (:duration current) time)]
(recur next-time (conj timed-events (assoc current :time time))
(rest events)))
To:
(if-let [current (first remaining)]
(recur (conj (+ (:duration current) time) timed-events (assoc current
:time time)) (rest events))
timed-events)
As a style thing, you might choose to be explicit about the loop/recur,
rather than having a multi-arity fn, e.g
(defn to-timed-events
[events]
(loop [result []
remaining events
time 0]
(if-let [current (first remaining)]
(recur (conj result (assoc current :time time)) (rest remaining) (+
(:duration current) time))
result)))
Derek
On Sunday, April 24, 2016 at 8:01:14 PM UTC+10, Olivier Scalbert wrote:
>
> Hi all,
>
> I am a Clojure beginner ....
> And I have an advice to ask !
>
> I have an array of events:
>
> (def events [
> {:id "1" :duration 100}
> {:id "2" :duration 200}
> {:id "3" :duration 300}
> ])
>
> I wanted to transform this array into:
> [
> {:id 1, :duration 100, :time 0} ; event 1 starts at 0
> {:id 2, :duration 200, :time 100} ; event 2 starts when event 1 is
> finished, so at 100
> {:id 3, :duration 300, :time 300} ; event 3 starts when event 2 is
> finished, so at 100 + 200
> ]
>
> Here is the function code:
>
> (defn to-timed-events
> ([time events] (to-timed-events time [] events))
> ([time timed-events events]
> (if (empty? events)
> timed-events
> (let [current (first events)
> next-time (+ (:duration current) time)]
> (recur next-time (conj timed-events (assoc current :time
> time)) (rest events))
> ))))
>
> It seems to work, but it looks a bit long for what it is doing. Is it
> possible to improve it ?
>
> Thanks for your help,
>
> Olivier
>
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