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(ns com.widdindustries.timelines | |
"create timelines which are (possibly infinite) sequences of maps with a ::time key. | |
Multiple timelines can be merged into a single timeline | |
Zero dependency - BYO time lib | |
Demo in comment at the end | |
") | |
(defn merge-timelines [timelines] | |
(let [[tl-with-soonest & others] (sort-by (comp ::time first) (remove nil? timelines)) | |
[next-soonest & remainder] tl-with-soonest] | |
(if-not next-soonest | |
[] | |
(lazy-seq | |
(cons next-soonest | |
(merge-timelines (cons remainder others))))))) | |
(defn timeline [{:keys [start | |
end-pred next-tick]}] | |
(let [tl (iterate (fn [prev] | |
(update prev ::time | |
next-tick)) | |
start)] | |
(if end-pred | |
(take-while #(end-pred (::time %)) | |
tl) | |
tl))) | |
(comment | |
(require '[tick.alpha.api :as t]) | |
(def foo-timeline | |
(timeline {:start {::time (t/today) | |
:timeline-name "foo"} | |
:next-tick (fn [x] (t/>> x (t/new-period 2 :days)))})) | |
(def bar-timeline | |
(timeline {:start {::time (t/yesterday) | |
:timeline-name "bar"} | |
:next-tick (fn [x] (t/>> x (t/new-period 1 :days))) | |
:end-pred (fn [x] (t/<= x (t/>> (t/today) | |
(t/new-period 4 :days))))})) | |
; see bar is finite - only 6 in the seq | |
(take 10 bar-timeline) | |
(def foo-bar-timeline (merge-timelines [foo-timeline bar-timeline])) | |
; see foo and bar interleaved | |
(take 10 foo-bar-timeline) | |
) |
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