On Sat, Nov 26, 2016 at 09:05:44PM -0500, Bruno Franco wrote: > I was trying out the diff function and I noticed something: > > : (diff '(1 2 3 4) '(3 4)) > -> (1 2) > > but > > : (diff '(3 4) '(1 2 3 4)) > -> NIL > > I think this means that there is an order to the arguments of diff, where
It is analogous to the arithmetic difference, where A - B is not the same as B - A. > the second argument must be the shortest. This is not the case. The length is not relevant: : (diff (1 2 3) (8 6 4 2)) -> (1 3) > I also tried this: > > : (diff (1 2 3 4) 2) > -> (1 3 4) > > So, why does diff work even if the second argument isn't a list? This is a result of how 'diff' is implemented internally. It takes all elements into account, I think it is a welcome feature. Note that this also works: : (diff (1 2 3) (1 . 2)) -> (3) ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
