I'm not sure if I understand what you're tying to do correctly, but here's
one way to do it (or one way to do something, at least):
(define (process-list-of-lists list-of-lists)
(apply map
(λ args
(apply max args))
list-of-lists))
(process-list-of-lists
`((55 1 2)
(8 13 7)
(3 9 42))))
;; returns '(55 13 42)
Of course, you could also use explicit recursion instead of map and apply,
but you don't "overwrite" the result of a previous recursive call in either
case.
On Sat, Oct 22, 2016 at 2:04 PM <meino.cra...@gmx.de> wrote:
> Hi,
>
> (I am still a newbie ... )
>
> If I remember one rule of functional programming
> correctly, it says:
> Instead of changeing data - create new data.
>
> Suppose I have a list of list. Each "sublist" is
> made of a greater amount (but identical count) of
> exact numbers (integers).
>
> I want to process these data recursively and if
> all is done I want to get back a list of numbers
> (same count of numbers as in each sublist), which
> represents the maximum of all numbers of that "position"
> in all sublists.
>
> If I want to make this purely (may be inpractical) functional,..
> I see (as a newbie) the following problem.
> From two numbers as input I have to build a maximum and
> have to feed that into the next circle of recursion as
> one of the numbers to compare.
> Each time a new maximum is found I have to overwrite the
> old one.
> This contradicts the rule "Dont change data, create new one."
>
> How can I get out of this?
>
> Cheers
> Meino
>
>
>
>
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