Hi Guys,
One of the things that has struck me about clojure, by virtue of being
a lisp, is the concision of the code - I really find it very
attractive. However yesterday I found something that I couldn't work
out how to do in a concise manner. Clearly commenting the code was a
priority once I got it working, however I'd like to ensure I'm doing
this correctly.
Much of my functional experience comes from JS and dealing with the
immutability of our data structures is a very interesting learning
process.
I have a map (a sorted map) which maps an int to a map. The inner map
contains a vector of data to which I want to conj elements into.
{ 0 {:title "some str"
:meetings [{ ... meeting data ... }
{ ... meeting data ... }
{ ... meeting data ...}]}
1 {:title "some other str"
:meetings [{ ... meeting data ... }
{ ... meeting data ... }
{ ... meeting data ...}]}
.....
n {:title "some n str"
:meetings [{ ... meeting data ... }
{ ... meeting data ... }
{ ... meeting data ...}]}}
In JS I'd have a loop which looks somewhat like this (assume the data
above is called storedData and that newData has the data which I wish
to insert into storedData);
newData.forEach(function(data) {
var key = .... ;
if (!storedData[key])
storedData[key] = {title: "title"}, meetings:[]}
storedData[key].meetings.push(data) ;
})
In clj, I've ended up with something along the lines of the following
(edited from what I have in my code base to match the JS example
above):
(loop [data (sorted-map)
collection newData
meeting (first collection)]
(def key ( .... ))
(if (not (nil? (next collection)
(recur (cond (not (nil? (data key)))
(assoc data key
(assoc (data key)
:meetings
(conj ((data key) :meetings) meeting)))
(true? true)
(conj data [key {:title "some str" :meetings [meeting]}])))
data))
The middle section, with the assoc(es) and conj, just doesn't read as
nicely as the rest of my clojure. Is this a symptom of my data
structure or is there a more concise way to conj my data into these
inner vectors?
Also, as a secondary concern, I read on here a while ago that when you
find yourself typing "((" it's a sign of an issue - how, given the
data structure I've to work with, woud you access the title of a value
if not using that "((" syntax, i.e. ((data key) :title)?
Cheers,
mike
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