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(elisp)Eval During Compile

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Evaluation During Compilation
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   These features permit you to write code to be evaluated during
compilation of a program.

 - Special Form: eval-and-compile body
     This form marks BODY to be evaluated both when you compile the
     containing code and when you run it (whether compiled or not).

     You can get a similar result by putting BODY in a separate file
     and referring to that file with `require'.  That method is
     preferable when BODY is large.

 - Special Form: eval-when-compile body
     This form marks BODY to be evaluated at compile time but not when
     the compiled program is loaded.  The result of evaluation by the
     compiler becomes a constant which appears in the compiled program.
     If you load the source file, rather than compiling it, BODY is
     evaluated normally.

     *Common Lisp Note:* At top level, this is analogous to the Common
     Lisp idiom `(eval-when (compile eval) ...)'.  Elsewhere, the
     Common Lisp `#.' reader macro (but not when interpreting) is closer
     to what `eval-when-compile' does.