2-2, Common Lisp - rextester

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;gnu clisp  2.49.60
#|2.	Написать функцию, которая по списку вида:
- фамилия
- улица
- номер дома
Сформирует список однофамильцев, проживающих на заданной улице.
|#

(defun extract-street (data street)
    (loop for x in data 
          when (string= (second x) street)
          collect x 
    )
)

(defun namesakes (data-street)
    (let (name))
    (let (ls))
    (setf ls (list))
    (let (j))
    (let (x)) (let (y))
    (let (len1)) (setf len1 (length data-street))
    (let (len2)) 
    (loop while (not (null data-street))
          do (setf x (first data-street))
          do (setf ls (list x))
          do (setf data-street (delete x data-street :count 1))
          do (setf j 0)
          do (setf len2 (length data-street))
          (loop while (< j len2)
                do (setf y (nth j data-street))
                if (string= (first x) (first y))
                          do (decf len2) and
                          do (nconc ls (list (nth j data-street))) and
                          do (setf data-street (delete y data-street :count 1))
                      else 
                        do (incf j)
                       )
          when (> (length ls) 1)
                 collect ls
                )
     )

(let (data))

(setf data '(("Holmes" "Baker" 221) ("Holmes" "Baker" 222) ("Adler" "Hewston" 22) ("Watson" "Baker" 221) ("Watson" "Baker" 222) ("Holmes" "Hewston" 23) ("Adler" "Hewston" 23) ("Holmes" "Baker" 223) ("Adler" "Baker" 222)))
(let (street))
(setf street "Baker")

(print (namesakes (extract-street data street)))

[ + ] Show input
Absolute running time: 0.15 sec, cpu time: 0.02 sec, memory peak: 9 Mb, absolute service time: 0,2 sec