Clojure: Implementing Seqable for an existing java class

Question

I am trying to make a core java class implement an interface. I am trying something along the lines of:

(extend-protocol clojure.lang.Seqable
  java.lang.Integer
  (seq [this] (seq (str this))))

but this does not seem to work because Seqable is just an interface and not a protocol. Is it possible to make (seq 123) work? how was seq implemented for java.lang.Strings?

proxy also does not seem capable of doing this.

I know I must be missing somethnig really obvious here.

amalloy · Accepted Answer · 2013-01-06 03:16:27Z

2

Not possible. clojure.lang.RT/seqFrom has special cases for a number of java builtin types, like Collection and String, and you can't add your own for classes that don't implement Seqable directly.

answered Jan 6, 2013 at 3:16

amalloy

93k8 gold badges148 silver badges215 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

WuHoUnited Over a year ago

Thank you, I wonder whether it would have been possible when clojure was designed to make Seqable a protocol or whether it really had to be a special case.

BillRobertson42 Over a year ago

@WuHoUnited When Clojure was originally implemented, they did not have protocols. My understanding though, was that they used them with great success when implementing Clojurescript.

NielsK · Accepted Answer · 2013-01-06 09:23:32Z

0

If the java class implements Iterable, and is wrapped in seq, you could use it as a sequence, with certain restrictions.

answered Jan 6, 2013 at 9:23

NielsK

6,9561 gold badge26 silver badges46 bronze badges

Collectives™ on Stack Overflow

Clojure: Implementing Seqable for an existing java class

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related