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Title: From "The Little Schemer" to newLISP
Post by: cameyo on May 25, 2020, 02:15:13 AM

I am reading the book "The Little Schemer" (yes, i know newLISP is different from Scheme...but i'm learning)

Until chapter 8 i had no problem to translate the code in newLISP.

But now i have the following function:

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(define (rember-f test?)
    (lambda (a l)
      (cond
       ((null? l) '())
       ((test? (first l) a) (rest l))
       (true (cons (first l) ((rember-f test?) a (rest l)))))))

Calling it in the following way:

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((rember-f =) 'tuna '(shrimp salad and tuna salad))

I got an error:

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ERR: invalid function : (test? (first l) a)

Instead the correct output should be:

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(shrimp salad and salad)

Can you help me to solve this problem?

Thanks

cameyo

Title: Re: From "The Little Schemer" to newLISP
Post by: newBert on May 25, 2020, 04:01:43 AM

I think the definition of 'rember-f' is wrong.

A correct writing of this lambda would be :

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(define rember-f
  (lambda (test? a l)
    (cond
      ((null? l) '())
      ((test? (first l) a) (rest l))
      (true (cons (first l) (rember-f test? a (rest l)))))))

> (rember-f = 'tuna '(shrimp salad and tuna salad))
(shrimp salad and salad)

or (define (rember-f test? a l) (cond and so on ...))

Title: Re: From "The Little Schemer" to newLISP
Post by: cameyo on May 25, 2020, 04:51:11 AM

Thanks newBert.

Wrong method of passing parameters in my function.

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Forum => newLISP in the real world => Topic started by: cameyo on May 25, 2020, 02:15:13 AM