I want to create a nested map.
The function implementation I have is the following:
(defn thefunction [something value]
;;"something" is for i.e: (something2 something3) ;it's a seq, could have more values.
;;here I want the code to create a map like this >> {:something2 {:something3 value}}
I don't know how to implement it to get the map above. I'm new at clojure.
Thanks.
There's an assoc-in function in clojure.core you can use for this. assoc-in takes an associative data structure (e.g. map, vector), a key-path sequence, and a value to associate at the end of the nested path.
In your case there's no pre-existing structure to associate into, but that's fine because assoc-in uses assoc internally which will create a map if the first argument is nil:
(assoc nil :foo 1)
=> {:foo 1}
So you can define your function in terms of assoc-in with nil as its first argument:
(defn the-function [something value]
(assoc-in nil something value))
And for example if your something sequence consists of symbols:
(the-function '(something2 something3) 'value)
=> {something2 {something3 value}}
(the-function (map str (range 4)) :foo)
=> {"0" {"1" {"2" {"3" :foo}}}}
I want to access the value using
(get-in theMap [:something2 :something3])but it returns nil
Typically you'll see Clojure map literals use keyword keys, although many other types will also work fine, and they can be mixed:
(the-function [:foo "bar" 'baz] \z)
=> {:foo {"bar" {baz \z}}}
You could convert your input sequence into keywords either before you call your function (or inside it if you want to enforce keyword-keys for all callers).
(the-function (map keyword '(something2 something3)) 'value)
=> {:something2 {:something3 value}}
(get-in *1 (map keyword '(something2 something3)))
=> value
Unlike many languages, clojure allows you to use collection literals as the return value of a function with no extra overhead, so for example a function to create a nested map could be as simple as
(defn i-make-a-nested-map []
{1 {:a {:b 2}}})
and that can use arguments to the function anywhere in there:
(defn i-make-a-nested-map [I'm-a-function-argument]
{1 {:a {:b I'm-a-function-argument}}})
so your question very nearly contains it's own answer where you wrote:
(defn thefunction [something value]
{:something2 {:something3 value}})
There are useful function for manipulating keywords if you need to add the numbers to the end of the keyword passed in. They are name str and keyword
assoc-infor this:(assoc-in nil [:foo :bar] 1)=>{:foo {:bar 1}}.