From: Robert Klemme <bob.news@...>
Date: 2005-09-16T00:51:35+09:00
Subject: Re: Math: sum and faculty

Martin DeMello wrote:
> Robert Klemme <bob.news@gmx.net> wrote:
>>
>> To sum up, #sum seems too specialized.  #inject is there and does
>> the job quite nicely - and easily.
>
> Actually, something in between would be quite nice in terms of code
> aesthetics. I'm thinking of the specialised but very common case of a
> binary accumulator and a unary function, thus (calling it 'accumulate'
> for want of a better name):
>
> sum = enum.accumulate(0, :+) {|x| f(x)}

The difference isn't really that big, is it?
sum = enum.inject(0) {|s,x| s + f(x)}

> collect = enum.accumulate([], :<<) {|x| f(x)}

I prefer
collect = enum.map {|x| f(x)}
collect = enum.collect {|x| f(x)}

> and if you leave off the block, it simply applies f(x) = x. It avoids
> cluttering the block with the accumulator the way inject does.

Personally I don't find the "s +" to be cluttering the block.  At least
not enough to justify adding this to Enumerable.  My 0.02EUR...

Kind regards

    robert