Function Scheme（DrRacket）-用另一个函数调用广义/抽象函数

作为参考，我正在使用DrRacket使用Scheme编程

对于这个问题，我制作了一个广义/抽象函数（不使用高阶函数和/或lambda），称为函数

按位置点计数的
计数，定义如下：

(define listofCandidates
  (list "Blake" "Ash" "Bob" "Will" "Joey"))

;; Signature: tally-by-place-points: 
;;              list-of-candidates list-of-votes -> list-of-Voting-Tallies
;; Purpose: Consumes a list of candidate names and a list of votes and 
;;          produces a list of voting-tallies.
;;          (Points-Per-Place strategy).
;; Tests:
(check-expect (tally-by-place-points empty empty) empty)
(check-expect (tally-by-place-points listofCandidates listofVotes) 
              (cons (make-voting-tally "Blake" 7)
               (cons (make-voting-tally "Ash" 3)
                (cons (make-voting-tally "Bob" 5)
                 (cons (make-voting-tally "Will" 1)
                  (cons (make-voting-tally "Joey" 2) empty))))))
;; Define:
(define (tally-by-place-points aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (total-points-for (first aloc) alov))
                (tally-by-place-points (rest aloc) alov))]))

这就是我想到的（不确定是否正确）：

;; Signature: tally-by: (helper function)
;;              list-of-candidates list-of-votes -> list-of-Voting-Tallies
;; Purpose: Consumes a helper function, a list of candidate names, 
;;          and a list of votes and produces a list of voting-tallies.
;; Define:
(define (tally-by helper aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (tally-by helper (first aloc) alov))
                (tally-by helper (rest aloc) alov))]))

;; Signature: tally-by-place-points: 
;;              list-of-candidates list-of-votes -> list-of-Voting-Tallies
;; Purpose: Consumes a list of candidate names and a list of votes 
;;          and produces a list of voting-tallies.
;;          (Points-Per-Place strategy).
;; Tests:
(check-expect (tally-by-place-points empty empty) empty)
(check-expect (tally-by-place-points listofCandidates listofVotes) 
              (cons (make-voting-tally "Blake" 7)
               (cons (make-voting-tally "Ash" 3)
                (cons (make-voting-tally "Bob" 5)
                 (cons (make-voting-tally "Will" 1)
                  (cons (make-voting-tally "Joey" 2) empty))))))
;; Define:
(define (tally-by-place-points aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (tally-by (first aloc) alov))
                (tally-by (rest aloc) alov))]))

我应该注意，这是我所指的帮助函数，
总分为
：

;; Signature: total-points-for: string list-of-strings -> number
;; Purpose: Consumes a name and a list of votes and produces the
;;          number of points that the given name has received
;;          using a points-per-place strategy.
;; Tests:
(check-expect (total-points-for "Ash" empty) 0)
(check-expect (total-points-for "Ash" listofVotes) 3)
(check-expect (total-points-for "Blake" listofVotes) 7)
(check-expect (total-points-for "Bob" listofVotes) 5)
(check-expect (total-points-for "Will" listofVotes) 1)
(check-expect (total-points-for "Joey" listofVotes) 2)
(check-expect (total-points-for "Brad" listofVotes) 0)
;; Define:
(define (total-points-for cand alov)
  (cond
    [(empty? alov) 0]
    [(string=? (vote-choice1 (first alov)) cand) 
                        (+ 3 (total-points-for cand (rest alov)))]
    [(string=? (vote-choice2 (first alov)) cand) 
                        (+ 2 (total-points-for cand (rest alov)))]
    [(string=? (vote-choice3 (first alov)) cand) 
                        (+ 1 (total-points-for cand (rest alov)))]
    [else (total-points-for cand (rest alov))]))

我现在必须修改
tallybyplacepoints
函数，以调用我刚刚创建的广义/抽象函数
tallybys
。我应该注意签名、目的和支票都是正确的。这是我提出的函数，尽管定义不正确：

;; Signature: tally-by: (helper function)
;;              list-of-candidates list-of-votes -> list-of-Voting-Tallies
;; Purpose: Consumes a helper function, a list of candidate names, 
;;          and a list of votes and produces a list of voting-tallies.
;; Define:
(define (tally-by helper aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (tally-by helper (first aloc) alov))
                (tally-by helper (rest aloc) alov))]))

;; Signature: tally-by-place-points: 
;;              list-of-candidates list-of-votes -> list-of-Voting-Tallies
;; Purpose: Consumes a list of candidate names and a list of votes 
;;          and produces a list of voting-tallies.
;;          (Points-Per-Place strategy).
;; Tests:
(check-expect (tally-by-place-points empty empty) empty)
(check-expect (tally-by-place-points listofCandidates listofVotes) 
              (cons (make-voting-tally "Blake" 7)
               (cons (make-voting-tally "Ash" 3)
                (cons (make-voting-tally "Bob" 5)
                 (cons (make-voting-tally "Will" 1)
                  (cons (make-voting-tally "Joey" 2) empty))))))
;; Define:
(define (tally-by-place-points aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (tally-by (first aloc) alov))
                (tally-by (rest aloc) alov))]))

我希望有人能够帮助我完成我的
tall by
和修改的
tall by place points
函数定义，因为我不确定该怎么做。
在tall by place points中，您调用
（第一次aloc）alov的总积分）
来获取位置点。在
tally by
中，如果您将
总分作为参数
helper
传递，您应该能够做到完全相同的操作。因此，您需要将对
的
总分的引用替换为
helper
，并在递归时传递helper：

(define (tally-by helper aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (helper (first aloc) alov))
                (tally-by helper (rest aloc) alov))]))

在
tally by place points
中，使用
tally by
只需调用
tally
by，并使用正确的
辅助对象得到的参数即可：

(define  (tally-by-place-points aloc alov)
  (tally-by total-points-for aloc alov))

顺便说一句，你提到你使用的是哪种语言是模棱两可的。从语法上看，您很可能是在DrRacket中编程racket。我猜你的第一行是
#lang scheme
（
#！scheme
）或者
#！racket
，是同义词，不是正式的Scheme语言。对于实际的Scheme语言，您需要使用
#！r6rs
或
#！R5R
，并根据其进行编程
 按您调用的地点点进行理货（第一个aloc）alov的总分）
以获取地点点。在
tally by
中，如果您将
总分作为参数
helper
传递，您应该能够做到完全相同的操作。因此，您需要将对
的
总分的引用替换为
helper
，并在递归时传递helper：

(define (tally-by helper aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (helper (first aloc) alov))
                (tally-by helper (rest aloc) alov))]))

在
tally by place points
中，使用
tally by
只需调用
tally
by，并使用正确的
辅助对象得到的参数即可：

(define  (tally-by-place-points aloc alov)
  (tally-by total-points-for aloc alov))

顺便说一句，你提到你使用的是哪种语言是模棱两可的。从语法上看，您很可能是在DrRacket中编程racket。我猜你的第一行是
#lang scheme
（
#！scheme
）或者
#！racket
，是同义词，不是正式的Scheme语言。对于实际的Scheme语言，您需要使用
#！r6rs
或
#！R5R
，并根据其进行编程
 按您调用的地点点进行理货（第一个aloc）alov的总分）
以获取地点点。在
tally by
中，如果您将
总分作为参数
helper
传递，您应该能够做到完全相同的操作。因此，您需要将对
的
总分的引用替换为
helper
，并在递归时传递helper：

(define (tally-by helper aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (helper (first aloc) alov))
                (tally-by helper (rest aloc) alov))]))

在
tally by place points
中，使用
tally by
只需调用
tally
by，并使用正确的
辅助对象得到的参数即可：

(define  (tally-by-place-points aloc alov)
  (tally-by total-points-for aloc alov))

顺便说一句，你提到你使用的是哪种语言是模棱两可的。从语法上看，您很可能是在DrRacket中编程racket。我猜你的第一行是
#lang scheme
（
#！scheme
）或者
#！racket
，是同义词，不是正式的Scheme语言。对于实际的Scheme语言，您需要使用
#！r6rs
或
#！R5R
，并根据其进行编程
 按您调用的地点点进行理货（第一个aloc）alov的总分）
以获取地点点。在
tally by
中，如果您将
总分作为参数
helper
传递，您应该能够做到完全相同的操作。因此，您需要将对
的
总分的引用替换为
helper
，并在递归时传递helper：

(define (tally-by helper aloc alov)
  (cond
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (helper (first aloc) alov))
                (tally-by helper (rest aloc) alov))]))

在
tally by place points
中，使用
tally by
只需调用
tally
by，并使用正确的
辅助对象得到的参数即可：

(define  (tally-by-place-points aloc alov)
  (tally-by total-points-for aloc alov))

顺便说一句，你提到你使用的是哪种语言是模棱两可的。从语法上看，您很可能是在DrRacket中编程racket。我猜你的第一行是
#lang scheme
（
#！scheme
）或者
#！racket
，是同义词，不是正式的Scheme语言。对于实际的Scheme语言，您需要使用
#！r6rs
或
#！R5R
，并根据其进行编程
 抽象是一种纯粹的语法转换！相反，这只是测试版的减少：

..... a .....     ==>     (λa.  ..... a ..... ) a

也就是说，您只需将使用的某个实体放入函数的参数中，并在函数调用中将该实体作为参数传递。这样，以前特定的东西现在被概括，变成一个参数，抽象为：

(define (tally-by-place-points      aloc alov)
  (cond         ; ~~~~~~~~~~~~
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (total-points-for (first aloc) alov))
                           ;       ^^^^^^^^^^^^^^^^^
                (tally-by-place-points (rest aloc) alov))]))

被改写为

(define (tally-by   place-points    aloc alov)
  (cond         ;   ~~~~~~~~~~~~
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (place-points     (first aloc) alov))
                           ;       ^^^^^^^^^^^^^^^^
                (tally-by-place-points (rest aloc) alov))]))

所以电话

(tally-by   total-points-for   aloc alov)

相当于上一次呼叫

(tally-by-place-points         aloc alov)

这当然需要在递归调用中进行整理-它也需要进行转换：

(define (tally-by   place-points    aloc alov)
  (cond         ;   ~~~~~~~~~~~~
    [(empty? aloc) empty]
    [else (cons (make-voting-tally (first aloc) 
                                   (place-points     (first aloc) alov))
                (tally-by   place-points   (rest aloc) alov))]))
                        ;   ~~~~~~~~~~~~

因为我们将
（按地点点理货…
）替换为
（按地点点理货…
——无处不在

当然，我们现在可以用我们想要的任何名称（只要名称是唯一的）重命名
placepoints
参数。
抽象是一种纯粹的语法转换！它只是beta-reduce