comp.lang.lisp

William James

12/1/2015 6:16:00 PM

WJ wrote:

> Frank Schwieterman wrote:
>
> > > I am Lisp beginner and I am doing a simple execise on lisp. I was asked
> > > to write a lisp program , by using either recursion or do, to return
> > > true if the difference between each successive pair of the them is 1.
> > >
> > > ie:
> > >
> > > > (difference '(2 1))
> > > T
> > > > (difference'(3 4 5 6 5 4))
> > > T
> > > > (differnce '(3 4 5 3))
> > > NIL
> > >
> > > If anyone can let me see the code, it will help me catch up this
> > > language. Thanks,
> > >
> > > Joe
> > >
> > >
> >
> > I looked up your professor's address and told him to recognize the following
> > solution as being plagiarized:
> >
> > (defun difference (param)
> > (if (> (length param) 1)
> > (if (<= (abs (- (first param) (first (rest param)))) 1 )
> > (difference (rest param))
> > nil
> > )
> > T
> > )
> > )

Ocaml:

let rec difference = function
[] | [_] -> true
| a::b::xs when 1 = abs (a-b) -> difference (b::xs)
| _ -> false ;;

# difference [0;1;2;3;2];;
- : bool = true
# difference [0;1;2;3;2;0];;
- : bool = false
# difference [9;8;7;8;9];;
- : bool = true
# difference [0;0];;
- : bool = false
# difference [0];;
- : bool = true
# difference [];;
- : bool = true

--
You have politicians saying that ... as many Africans as want to come into
Sweden should be able to come.... They've already said that everybody from
Syria can come to Sweden.... [T]hey are actually thinking of commandeering
people's vacation homes because they need more housing for immigrants.
--- Dr. Kevin MacDonald (http://lnrlive.com/tpc/tpc201...)