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copied!<p>This is not an answer to your question, but in the interest of writing "nice" clojure code, I wanted to point out a few things with your example.</p> <p>One of the benefits of the functional style is the ability to compose functions together. But if you take a look at the functions you've written, they individually don't do much without depending on functionality provided elsewhere. </p> <p>For example, <code>stream-builder</code> just returns a two-element list of <code>n</code> and an anonymous function to handle pseudo-recursion.</p> <p>My guess is that you were trying to go for a lazy sequence, but doing it that way requires support functions that are aware of the implementation details to realize the next element, namely, <code>stream</code> and <code>second$</code>. Thankfully you can instead accomplish it as follows:</p> <pre> (defn stream-builder [f x] ; f is idiomatic for a function arg (lazy-seq ; n is idiomatic for a count, so use x instead (cons x (stream-builder f (f x))))) </pre> <p>The above will actually return an infinite sequence of values, so we need to pull out the limiting behavior that's bundled inside <code>stream</code>:</p> <pre> (defn limit [n coll] ; coll is idiomatic for a collection arg (lazy-seq ; flipped order, fns that work on seqs usually take the seq last (when (pos? n) (when-let [s (seq coll)] (cons (first s) (limit (dec n) (next s))))))) </pre> <p>The above will <i>lazily</i> return up to <code>n</code> elements of <code>coll</code>:</p> <pre> user=> (limit 5 (stream-builder inc 1)) (1 2 3 4 5) </pre> <p>In the end, each function does one thing well, and is composable with other functions:</p> <p>Finally, you defined <code>odd</code> to be the lazy sequence of odd integers. The danger is that sequence is going to stick around as it gets realized (this is known as "holding onto the head" of a sequence). This can unnecessarily take up excess memory to hold onto every element ever realized, and prevents garbage collection.</p> <p>To solve this, either do not def the lazy sequence, or def it with the limit, e.g.:</p> <pre> (def odds (limit 23 (stream-builder #(+ 2 %) 1))) </pre> <p>For future reference, what we have just written is available in the core lib as <code>iterate</code> and <code>take</code>, respectively:</p> <pre> user=> (take 5 (iterate inc 1)) (1 2 3 4 5) </pre>

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