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copied!<p>The recursive version is fine, but limited to <code>List</code> (with limited changes, it would work well on <code>LinearSeq</code>).</p> <p>If it was implemented in the standard library (would make sense) it would probably be done in <code>IterableLike</code> and have a completely imperative implementation (see for instance method <code>find</code>)</p> <p>You can interrupt the <code>foldLeft</code> with a <code>return</code> (in which case you need only the previous element and not boolean all along)</p> <pre><code>import Ordering.Implicits._ def isOrdered[A: Ordering](seq: Seq[A]): Boolean = { if (!seq.isEmpty) seq.tail.foldLeft(seq.head){(previous, current) => if (previous > current) return false; current } true } </code></pre> <p>but I don't see how it is any better or even idiomatic than an imperative implementation. I'm not sure I would not call it imperative actually. </p> <p>Another solution could be </p> <pre><code>def isOrdered[A: Ordering](seq: Seq[A]): Boolean = ! seq.sliding(2).exists{s => s.length == 2 && s(0) > s(1)} </code></pre> <p>Rather concise, and maybe that could be called idiomatic, I'm not sure. But I think it is not too clear. Moreover, all of those methods would probably perform much worse than the imperative or tail recursive version, and I do not think they have any added clarity that would buy that. </p> <p>Also you should have a look at <a href="https://stackoverflow.com/q/7830471/754787">this question</a>.</p>

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