What you are asking for seems like alpha congruence, but less restrictive. How much less restrictive? That depends on you definition of "the same pattern". In length you have "(car l)" and in length you have "1". Do they have the same structure? That, of course depends on the definition of car (it may have been redefined). If you suppose that commonly used functions are not redefined, you might argue that both"car l" and "1" are atomic-like things. So you need to define "atomic-like". Consider also: (define (flatten x) (cond ((null? x) '()) ((pair? x) (append (flatten-helper (car x)) (flatten (cdr x)))) (else (list x)))) (define flatten-helper flatten) I suppose that in your opinion, flatten does not have the same structure as sum and length. You need to know that (flatten-helper (car x)) is not "atomic-like". Just some thoughts, Jos
_____ From: users-boun...@racket-lang.org [mailto:users-boun...@racket-lang.org] On Behalf Of Mohammad Mustaqeem Sent: viernes, 30 de noviembre de 2012 9:24 To: users@racket-lang.org Subject: [racket] Matching patterns of two function I have a problem in matching the patterns of two functions. I want to match two function whether they are following the same pattern or not? e.g. The "sum" function that computes the sum of all the elements of the list and "length" function that computes the length of the list. Here, we see that both the functions have same pattern. (define (sum l) (cond[(empty? l)0] [else (+ (car l)(sum (cdr l)))])) (define (length l) (cond[(empty? l)0] [else (+ 1(length (cdr l)))])) How can we determine that both has same pattern or not? I want to write a function that takes these functions as input and tells whether they have same pattern or not.
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