From: Pixel <pixel_@...>
Date: 2000-02-15T13:37:57+01:00
Subject: [ruby-talk:01378] Re: nice sample for functional stuff

gotoken@math.sci.hokudai.ac.jp (GOTO Kentaro) writes:

[...]

> >       def sum
> >         inject(0) {|n, i| n += i }
                                ^^ why ??

        inject(0) {|n, i| n + i }

seems enough to me, uh?

> >       end
> >     end
> 
> That is not bad though, I was interested in how I can sum up the
> non-numerical elements.  The solution above uses an assumption such
> that the result is 0 if enum.size == 0

and also that each element are numbers, otherwise you need

def sum
  inject(0) {|n, i| n + i.to_i }
end

but doesn't help much


> but [ruby-talk:01364] doesn't.

uh? your solution gives ([].sum == nil), tis still not the best. mine has the
same problem

l = [1]
l.sum + 1 #=> 2

l.shift
l.sum + 1 #=> Exception

-> [].sum should raise an exception

(perl has no such problem as "" is 0 is undef is ... :)