I guess it's time to get acquainted with foldr and foldl.

I assume it goes something like this:

( 1 `const`(2 `const`(3 `const`(4 `const`(5 `const`(undefined `const` 0))))))

                                                              ( 5 `const` undefined)

                                               (4 `const` 5)    

                                (3 `const` 4)

                ( 2 `const` 3)

(1 `const`2)

= 1

What i don't get is the opposite:

in my mind this should go like this: 

((((((0`const`1)`const` 2) `const` 3 )`const` 4)`const`  5) `const` undefined)

                    (0 `const`2)

                                      (0`const` 3)            

                                                      ( 0`const`4)

                                                                       (0`const` 5)

                                                                                      (0 `const` undefined )

= 0

I have been told that the main difference between foldl and foldr is that foldl needs to evaluate the whole spline before it continues. And i guess that has something to do with it. What I don't understand is WHY foldl need to do this and foldr doesn't.

thanks in advance!

best,