The `get` function will accept `nil` as the map argument and return `nil`,
but invoking `nil` will throw a NullPointerException.
By convention, people use `get` when they don't know what the map argument
is, since it might be nil. And we use keywords as functions when they are
literals, like (:foo m).
(let [m (...something that might return a map or nil...)]
(get m "some key")) ; returns nil or value
(let [m (...something that might return a map or nil...)]
(m "some key")) ; might throw exception
All forms of map lookup support a default argument if the key is not found:
user=> (let [m {:a 1 :b 2}] (m :c "not found"))
"not found"
user=> (let [m {:a 1 :b 2}] (:c m "not found"))
"not found"
user=> (let [m {:a 1 :b 2}] (get m :c "not found"))
"not found"
–S
On Tuesday, September 13, 2016 at 7:58:14 AM UTC-4, Rickesh Bedia wrote:
>
> Hi everyone,
>
> I am new to Clojure and have been playing around with it for a little
> while. I have seen that (get [3 2 1] 0) and ([[3 2 1] 0) both return the
> value 3. Similarly (get {:a 0 :b 1} :b) and ({:a 0 :b 1} :b) return 1.
>
> I was wondering if anyone could explain why the get function is useful or
> maybe an example?
>
> Apologies in advance if this question is due to ignorance and I haven't
> reached the level where this function is used.
>
> Thanks in advance
>
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