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21 lines
598 B
21 lines
598 B
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Exercise 2.54: Two lists are said to be
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equal? if they contain equal elements arranged in the same order. For
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example,
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(equal? '(this is a list)
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'(this is a list))
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is true, but
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(equal? '(this is a list)
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'(this (is a) list))
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is false. To be more precise, we can define equal? recursively in
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terms of the basic eq? equality of symbols by saying that a and
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b are equal? if they are both symbols and the symbols are
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eq?, or if they are both lists such that (car a) is equal?
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to (car b) and (cdr a) is equal? to (cdr b). Using
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this idea, implement equal? as a procedure.102
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