CODEWITHSUNDEEP
schemesicp
Liu Weibo
Liu Weibo

Reputation: 466

What's the different between '(a b (c)) and (list 'a 'b (list 'c))

I am working on exercise 2.57 and I have such a problem what's the different between '(a b (c)) and (list 'a 'b (list 'c)) since they look exactly the same in the scheme interpreter?

1 ]=> (eq? '(a b (c)) (list 'a 'b (list 'c)))

;Value: #f

1 ]=> '(a b (c))

;Value 2: (a b (c))

1 ]=> (list 'a 'b (list 'c))

;Value 3: (a b (c))

1 ]=>

Upvotes: 0

Views: 126

Answers (1)

Amadan
Amadan

Reputation: 198446

Hint: what is (eq? (list 1) (list 1))?

eq? only tests object identity. Two separately constructed lists are not the same list, even if their contents are the same. Use equal? for value equality:

(equal? '(a b (c)) (list 'a 'b (list 'c)))
; => #t

Upvotes: 1

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