Question

I’m new to Clojure and trying to learn the basics. One thing that tripped me up is understanding the correlation between the data structures and the functions they use.

For instance, if I create a new Vector:

(def my-vec [1 2 3])

Then when I try to call my-vec:

(my-vec)

I get:

ArityException Wrong number of args (0) passed to: PersistentVector  clojure.lang.AFn.throwArity (AFn.java:437)

I know that I can pass an argument and it appears to be calling get but how do I know? What args does PersistentVector take and where do I find documentation about it?

I tried:

(doc PersistentVector)

But that returns nil.

Answer 1

Documentation can be found under IPersistentVector here:
http://clojure.org/data_structures

In particular:
Vectors implement IFn, for invoke() of one argument, which they presume is an index and look up in themselves as if by nth, i.e. vectors are functions of their indices.