Is there an application of foldr where the resulting expression evaluates to an identical copy of the original list?

Question

Hey so I have kind of been struggling with this question, i've been playing around with different combinations but I cannot seem to think of a function that will cause the list to produce itself. Does anyone have an idea?

Does this answer your question? [Scheme: Iterative process to reconstruct a list in original order?](https://stackoverflow.com/questions/63827368/scheme-iterative-process-to-reconstruct-a-list-in-original-order) — alinsoar, Nov 22 '20 at 21:32

score 2 · Accepted Answer · answered Nov 22 '20 at 22:10

2

Sure, it's pretty straightforward. You just have to use the same procedure that was used to construct the list in the first place: cons.

(define lst '(1 2 3 4 5))
(foldr cons '() lst)
=> '(1 2 3 4 5)

answered Nov 22 '20 at 22:10

Óscar López

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Thank you so much! I was actually a bit confused at first didn't think of it that way! – fintechgenie Nov 22 '20 at 22:34

Is there an application of foldr where the resulting expression evaluates to an identical copy of the original list?

1 Answers1