[racket] Racket guide

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Wed Sep 17 14:49:41 EDT 2014

On Sep 17, 2014, at 2:04 AM, mukesh tiwari wrote:

> Dear Racket Users,
> I am learning racket and I found little bit misleading statement on guide [1]. It says that "Both the my-length and my-map functions run in O(n) time for a list of length n.". Technically this statement is correct but when I read below
> "For a list with n elements, evaluation will stack up n (+ 1 ...) additions, and then finally add them up when the list is exhausted.
> You can avoid piling up additions by adding along the way. To accumulate a length this way, we need a function that takes both a list and the length of the list seen so far; the code below uses a local function iter that accumulates the length in an argument len".
> so just curious, shouldn't it be "Both the my-length and my-map functions run in O(n) space for a list of length n." ?

That's correct for straightforward versions of these functions. -- Matthias

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