Iterator blocks in Clojure?

Posted by Checkers on Stack Overflow See other posts from Stack Overflow or by Checkers
Published on 2010-05-02T12:50:09Z Indexed on 2010/05/03 6:58 UTC
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I am using clojure.contrib.sql to fetch some records from an SQLite database.

(defn read-all-foo []
  (with-connection *db*
    (with-query-results res ["select * from foo"]
       (into [] res))))

Now, I don't really want to realize the whole sequence before returning from the function (i.e. I want to keep it lazy), but if I return res directly or wrap it some kind of lazy wrapper (for example I want to make a certain map transformation on result sequence), SQL-related bindings will be reset and connection will be closed after I return, so realizing the sequence will throw an exception.

How can I enclose the whole function in a closure and return a kind of iterator block (like yield in C# or Python)?

Or is there another way to return a lazy sequence from this function?

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