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shakna

You have let [0], why would you need a special loop function?

[0] http://jtra.cz/stuff/lisp/sclr/let.html

Edit:

That is to say, this is a simplified reference, and loop is a macro, not a special form.

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I assume you're thinking about Schemes `(let loop (...) ...)`, but that doesn't exist in Common Lisp. CL:LOOP is a looping macro with its own small DSL.

    (loop :for i :below 5
          :when (evenp i) :collect i)
    ;=> (0 2 4)

That's a step up from loops with 'goto':

    (prog ((result '())
           (i 0))
      loop
      (when (>= i 5)
        (return (reverse result)))
      (when (evenp i)
        (push i result))
      (incf i)
      (go loop))

tagbody/go is implementation detail of macro expansion though.

prog + goto was two decades one of the main tools for loops in Lisp...

This response makes no sense. Most of the functions in that page are not special forms. And both "car" and "first" are included! And "cdr" and "rest". And there are other functions that can be trivially obtained by the composition of two functions.

Note that both CAR and CDR refer to parts of a CONS cell which does not necessarily represent a list.

That doesn't change the fact that car and first are two names for one single function (the same applies to cdr and rest). (The point is that the absence of loop cannot be explained because it's not "needed".)

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