What does this -> followed by the namespace before the name of a record in Clojure means?

Question

I have seen a following piece of code here

  (def token-store
      (redis-store/->RedisTokenStore secret-key 30 {:pool {} :spec {:host "127.0.0.1" :port 6379}}))

Can anyone explain what does this mean ?

RedisTokenStore is a record that implements TokenStore protocol and its methods. but what does this syntax mean, objects can be created with this syntax as well:

(RedisTokenStore. secret-key 30 {:pool {} :spec {:host "127.0.0.1" :port 6379}})

Then what differently is this symbol -> doing ? Why is it after a user defined namespace ?

I know as a macro, -> is used to

(-> 4 (+ 5)
      (- 6))

which translates to (- (+ 4 5) 6) and gives 3. but neither could I google a '->' or type something similar to search what this means.

Answer 1

->RedisTokenStore is a factory function for record RedisTokenStore. Clojure defines it automatically when record is defined.

Here is quote from official Clojure datatypes docs:

when a deftype/defrecord Foo is defined a corresponding function ->Foo is defined that passes its arguments to the constructor (versions 1.3 and later only)

So, ->RedisTokenStore is a helper function which simply calls RedisTokenStore. constructor. The only difference is that you should import RedisTokenStore class to call its constructor explicitly, while ->RedisTokenStore is an ordinary function and could be require'ed and then used as a part of redis-store namespace.

Update: As mattexx poined out in his answer, there is also map->RedisTokenStore factory function which takes a map as its sole argument.

Answer 2

RedisTokenStore is declared with defrecord in the namespace.

At the bottom of the defrecord doc:

Given (defrecord TypeName ...), two factory functions will be defined: ->TypeName, taking positional parameters for the fields, and map->TypeName, taking a map of keywords to field values.