A clue to the answer is in your statement that you "feed that [maximum] into the next circle of recursion." Notice that you're not overwriting the value in the current call, you're creating a new value that you feed into the new call in the "next circle". So the old one isn't being overwritten at all.
Justin On Oct 22, 2016 3:15 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 > > > > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
