Refactoring my macro in a schema

I study hygiene and I tried to make a simple cycle in the Scheme. I want to support three types of constructs as shown in the example below

(for i = 1 : (< i 4) : (++ i)
  (printf "Multiplication Table for ~s\n" i)
  (for j = 1 to 5
    (printf "~s * ~s = ~s\n" i j (* i j))))

I also want to support loops with filters like this:

(for k = 1 : 10 : (list even? (λ(x) (> x 4))) : (++ k)
  (print k))

I have it, but I see a lot of repetitions. Please help me remove the layoffs.

(define-syntax for
  (syntax-rules (= to :)
    [(for x = initial : final : conditions : increment body ...)
     (letrec ([loop (λ(x)
                      (when (<= x final)
                        (when (andmap (λ(condition) (condition x)) conditions)
                          body ...)
                        (loop increment)))])
       (loop initial))]
    [(for x = initial : condition : increment body ...)
     (letrec ([loop (λ(x)
                      (when condition
                        body ...
                        (loop increment)))])
       (loop initial))]
    [(for x = initial to n body)
     (for x = initial : (<= x n) : (+ x 1) body)]))
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1 answer

I do not see much repetition here. Only one. It can be deleted as follows:

(define-syntax for
  (syntax-rules (= to :)
    [(for x = initial : final : conditions : increment body ...)
     (for x = initial : (<= x final): increment
          (when (andmap (λ(condition) (condition x)) conditions)
            body ...))]
    [(for x = initial : condition : increment body ...)
     (letrec ([loop (λ(x)
                      (when condition
                        body ...
                        (loop increment)))])
       (loop initial))]
    [(for x = initial to n body)
     (for x = initial : (<= x n) : (+ x 1) body)]))
+7
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Source: https://habr.com/ru/post/1724243/


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