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clojuredeftype

Nested types in clojure?

In clojure, how do I type type hint a type that I have created? (I want to nest the types.)

e.g. I had thought that this would work:

(deftype A 
    [#^somePrimitive  someField])

(deftype B
    [#^A Avalue])

This brings up an error message:

Unknown location:
  error: java.lang.ClassNotFoundException: A

Note: clojure types are a new feature which currently exists only in the 'new' branch of clojure.

Edit: I was confused by the different ways of type hinting in clojure for java and clojure types. java classes are hinted as 

#^java.some.class

while clojure types are hinted as:

#^:some.Namespace/type
Solution

  • For each deftype, a type tag (basically a namespace-qualified keyword) is created so you don't have to AOT-compile your code before you can use the resulting class.

    If type A is in the current namespace, you can write it like this:

    (deftype B [^::A Avalue])

    For types in other namespaces, qualify the keyword using its namespace:

    (deftype B [^:user/A Avalue])