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copied!<p>You only mention the case where there are exactly 2 expressions to evaluate. What happens if there are 5?</p> <pre><code>;; returns first true value, evaluating only as many as needed (or (f x) (g x) (h x) (i x) (j x)) </code></pre> <p>Would you nest if-statements? I'm not sure how I'd do this in Python. It's <em>almost</em> like this:</p> <pre><code>any(c(x) for c in [f, g, h, i, j]) </code></pre> <p>except Python's <code>any</code> throws away the value and just returns <code>True</code>. (There might be a way to do it with <code>itertools.dropwhile</code>, but it seems a little awkward to me. Or maybe I'm just missing the obvious way.)</p> <p>(As an aside: I find that Lisp's builtins don't <em>quite</em> correspond to what their names are in other languages, which can be confusing. Lisp's <code>IF</code> is like C's ternary operator <code>?:</code> or Python's conditional expressions, for example, not their if-statements. Likewise, Lisp's <code>OR</code> is in some ways more like (but not exactly like) Python's <code>any()</code>, which only takes 2 expressions. Since the normal <code>IF</code> returns a value already, there's no point in having a separate kind of "if" that can't be used like this, or a separate kind of "or" that only takes two values. It's already as flexible as the less common variant in other languages.)</p> <p>I happen to be writing code like this right now, coincidentally, where some of the functions are "go ask some server for an answer", and I want to stop as soon as I get a positive response. I'd never use <code>OR</code> where I really want to say <code>IF</code>, but I'd rather say:</p> <pre><code>(setq did-we-pass (or (try-this x) (try-that x) (try-some-other-thing x) (heck-maybe-this-will-work x)) </code></pre> <p>than make a big tree of IFs. Does that qualify as "flow control" or "functional"? I guess it depends on your definitions.</p>

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