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Re: Aggregation (with GBY) is Relational Division

From: vc <boston103_at_hotmail.com>
Date: 7 Jun 2006 03:13:57 -0700
Message-ID: <1149675237.843400.41480@y43g2000cwc.googlegroups.com>

Frank Hamersley wrote:
> vc wrote:

> >> so does
> >>
> >> eg> foldr (+) 4 [1..3] produce 4+3+2+1 or 3+2+1+4?
> >
> > foldr (+) 4 [1..3] => 1 + (2 + (3 +4)) = 10

>
> or
>
> foldr (+) 4 [1..3] => 1 + (2 + (4 + 3)) = 10
>

No.

> or
>
> foldr (+) 4 [1..3] => (((4 + 3) + 2) + 1) = 10
>

No.

> ???

Take any non-commutative operation to see the difference.

>
> The question becomes does the leftness/rightness persist in the
> construction of the expression prior to evaluation. I must confess my
> past exposure to stack oriented processing of expressions is influencing
> my interest.
>
> Cheers, Frank.
Received on Wed Jun 07 2006 - 05:13:57 CDT

Original text of this message

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