Hi. Need help with creating the ‘for’ macro. It must take a parameter, an initial value, an end value, and a loop step. Macro must return amount of iteration. Various operations should take place inside it. It should be designed without leaks.The preliminary version looks like this:

(defmacro for ((param-name start-value end-value &optional (step1 1)) &body body)
  (let* ((func-name (gensym))
(start (gensym))
(param-name (gensym))
(comparison (if (< step1 0) '< '>))
(end (gensym))
(step (gensym))
(k (gensym)))
'(labels ((,func-name (,param-name ,start ,end ,step ,k)
(let ((new-exprs (progn ,@body))
(newK (+ 1 ,k)))
(if (,comparison ,end ,param-name)
(,func-name (+ ,param-name ,step) ,start ,end ,step newK)
newK))))
(,func-name ,param-name ,start-value ,end-value ,step1 0))))

I understand that it looks terrible. I don’t understand how you can access the parameter without violating the rule about leaks.

  • Revolutionary_UtenaOPB
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    1 year ago

    (defmacro for
      ((param-name start-value end-value &optional (step1 1)) &body body)
        (let* ((func-name (gensym))
               (comp (gensym))
               (comparison (if (< step1 0) '<= '>=))
               (start (gensym))
               (end (gensym))
               (step (gensym))
               (k (gensym)))
          `(let ((,start ,start-value)
                 (,comp ,comparison)
                 (,end ,end-value)
                 (,step ,step1))
            (labels ((,func-name (,param-name ,k)
                       (if (,comp ,end ,param-name)
                           (progn (progn ,@body)
                             (,func-name (+ ,param-name ,step)
                                         (1+ ,k)) ) ,k)))
            (,func-name ,start 0)))))

    Sorry man. I kinda fixed the issue. When I am trying to call macros, it return me error
    ; compilation unit finished

    ; Undefined functions:

    ; #:G1 #:G7

    ; Undefined variable:

    ; >=
    I don’t know how to deal with bounding <= or >= to generated variable.