请在计划中重构我的宏

Question

我正在学习卫生，并且试图在Scheme中做一个简单的循环。我想支持3种结构的如示例如下

(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)))) 

我也想for循环与过滤器这样的支持：

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

我有这个，但我可以看到大量的重复。请帮我删除冗余。

(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)])) 

Answer 1

我在这里看不到很多重复。只有一个。它可以这样删除：

(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)]))