Extending protocols for custom Java classes, maps and sequences in Clojure

Question

I have created a protocol in Clojure 1.2 that handles my own Java classes and has default handling for a generic java.lang.Object. The code looks something like:

(extend-protocol PMyProtocol
  my.java.ClassName
    (protocol-function [c]
      "My Java class result")

  java.lang.Object
    (protocol-function [c]
      "Default object result"))

How should I extend this to have special handling for the standard Clojure data structures (in particular maps, vectors and sequences)?

Michał Marczyk · Accepted Answer · 2010-08-02 15:02:59Z

4

All of Clojure's persistent data structures implement interfaces which extend clojure.lang.PersistentCollection. Clojure's transient collections implement clojure.lang.TransientCollection. You can extend your protocol to these as if you were extending it to a class (though dealing with just the persistent collections might make more sense).

answered Aug 2, 2010 at 15:02

Michał Marczyk

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2 Comments

kotarak Over a year ago

To name them explicitly in case different handling is necessary: c.l.IPersistentMap, c.l.IPersistentVector, c.l.IPersistentSet (there is some system in there...) and for sequences c.l.ISeq.

mikera Over a year ago

Thanks Michal and kotarak! I ended up using clojure.lang.IPersistentMap and clojure.lang.ISeq which are working well.

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