Common Lisp lambda表達式錯誤

Question

我想製作一個程序，它將重寫給定的行而不在輸出行中有重複項。我使用這個網站，作爲一個編譯器： https://www.tutorialspoint.com/execute_lisp_online.php

這裏是我的代碼

(SETQ X (LIST 2 -3 (LIST 4 3 0 2) (LIST 4 -4) (LIST 2 (LIST 2 0 2))-3))' 
(DEFUN SEARCHDEEP (WHAT WHERE) ;Function will find out if atom `WHAT`is in a row `WHERE` => works fine 
(COND 
    ((NULL WHERE) NIL) 
    (T (OR 
      (COND 
       ((ATOM (CAR WHERE)) (EQUAL WHAT (CAR WHERE))) 
       (T (SEARCHDEEP WHAT (CAR WHERE))) 
      ) 
      (SEARCHDEEP WHAT (CDR WHERE)) 
     ) 
    ) 
) 
) 

(DEFUN REMDOUBLES (INPUT OUTPUT) 
(
(COND 
    ((NULL INPUT) NILL) ;recursion exit 
    (T     ; funstion 
     (OR    ; step into or go forward 
      (COND 
       ((ATOM (CAR INPUT)) (COND 
             ((NOT (SEARCHDEEP (CAR INPUT) OUTPUT)) (APPEND OUTPUT INPUT)) ;if this atom wasn't added => append 
            ) 
       ) 
       (T (REMDOUBLES (CAR INPUT) OUTPUT)) ; step into (car input => list 
      ) 
      (REMDOUBLES (CRD INPUT) OUTPUT) ; go forward, car input is anatom 
     ) 
    ) 
) 
) 
) 

(SETQ OUT (QUOTE)) ;Empty row 
(REMDOUBLES X OUT) 
(PRINT OUT) 

我花了2小時以來檢查這些代碼，並在這裏其他的答案，堆棧，但我不知道是什麼我在這裏想念嗎？

我收到此錯誤：

*** - SYSTEM::%EXPAND-FORM:
(COND ((NULL INPUT) NILL)(T(OR (COND ((ATOM (CAR INPUT)) (COND ((NOT (SEARCHDEEP (CAR INPUT) OUTPUT))(APPEND OUTPUT INPUT)))) (T (REMDOUBLES (CAR INPUT) OUTPUT))) (REMDOUBLES (CRD INPUT) OUTPUT)))) should be a lambda expression

很抱歉的格式，我在函數式編程和Lisp新手，我不知道應該如何正確地完成。

Answer 1

您的代碼：

第一行：

(DEFUN REMDOUBLES (INPUT OUTPUT) 

下聯：你能解釋一下單括號應該做些什麼？

(

你記住基本的Lisp表達式的語法Lisp的？

(operator argument0 argument1 ... argumentn) 

這不是

((operator argument0 argument1 ... argumentn)) 

Sorry for the formatting, i am novice in functional programming and LISP, and i have no idea how it should be done properly.

下載從Touretzky介紹Lisp的書：https://www.cs.cmu.edu/~dst/LispBook/

然後瞭解有代碼的Lisp的樣子。

您還可以使用Lisp的格式化代碼爲您提供：

這是您的格式化代碼：

[4]> (pprint '(DEFUN SEARCHDEEP (WHAT WHERE) ;Function will find out if atom `WHAT`is in a row `WHERE` => works fine 
(COND 
    ((NULL WHERE) NIL) 
    (T (OR 
      (COND 
       ((ATOM (CAR WHERE)) (EQUAL WHAT (CAR WHERE))) 
       (T (SEARCHDEEP WHAT (CAR WHERE))) 
      ) 
      (SEARCHDEEP WHAT (CDR WHERE)) 
     ) 
    ) 
) 
)) 

這是格式化代碼：

(DEFUN SEARCHDEEP (WHAT WHERE) 
(COND ((NULL WHERE) NIL) 
    (T 
    (OR 
    (COND ((ATOM (CAR WHERE)) (EQUAL WHAT (CAR WHERE))) 
    (T (SEARCHDEEP WHAT (CAR WHERE)))) 
    (SEARCHDEEP WHAT (CDR WHERE)))))) 

但它會更好寫成：

(DEFUN SEARCHDEEP (WHAT WHERE) 
    (WHEN WHERE 
    (OR (IF (ATOM (CAR WHERE)) 
      (EQUAL WHAT (CAR WHERE)) 
      (SEARCHDEEP WHAT (CAR WHERE))) 
     (SEARCHDEEP WHAT (CDR WHERE)))))