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    <p><code>defn</code>, <code>defmacro</code>, <code>defstruct</code> and such are just macros for defining their corresponding structure, making it unnecessary to write boilerplate code. For example, <code>defn</code> makes it easier to write functions since you no longer have to worry about putting in the lambda term (which you can do in Scheme just by bracketing the arguments immediately after the name being defined):</p> <p>Scheme:</p> <pre><code>(define hello (lambda (name) (display (string-append "hello, " name)))) (define (hello name) (display (string-append "hello, " name))) </code></pre> <p>Clojure:</p> <pre><code>(def hello (fn [name] (println (str "hello, " name)))) (defn hello [name] (println (str "hello, " name))) </code></pre> <p>You can look at <code>defn</code> as a mnemomic device for <code>def</code> + <code>fn</code>. Such shortcuts make for less boilerplate coding and make the code just easier to read in general. I'm teaching someone how to program Scheme at the moment and I make them use the long forms so that they have in mind at all times what the language is doing (and will appreciate the work-saving macros all the more when they finally start using them).</p> <p>The <code>define</code> or <code>def</code> forms give a name to some expression that follows. The <code>lambda</code> or <code>fn</code> form gives the name a set of bindings when used within a <code>define</code> or <code>def</code> expression. That's where things start to get more complex and the use of macro forms keeps you sane and protects you from typing boredom.</p>
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    1. POWhat is the rationale behind using def and defn instead of just define?
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    1. COYour Scheme is wrong there -- both the function name and the argument should be parenthesized. In addition, your explanation is only a small part of the whole picture. The "sugared" version of Scheme's definitions is *not* just to avoid boilerplate code -- it is easier to use (especially for newbies) since the thing that is defined *looks like* its uses. In other words, you define something that looks like a symbolic template for later uses of the function.
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    2. COYou are right. Trying to keep too many diferent lisps in the head at once. Scheme is the odd lisp out on that particular bit of sugaring, and since I haven't been using Scheme much and have been avoiding the sugared form when I do, I blew it. Corrected.
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    3. COI had not noticed the little cognitive 'priming trick' being played by the sugared form, that pre-echoing future use of the function in an s-expression, neat. I had not noticed that, at least not consciously. Something always bothered me about that form, and now I know what it is. The priming trick depends on the brain understanding the syntax of `define` to be loosely having something to do with a s-expression rather than giving a value to a name (an atom). I guess it is that sub-consciously noted 'semantic imprecision' had made me uneasy.
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