From: Mathieu Bouchard <matju@...>
Date: 2000-06-06T06:14:30-04:00
Subject: [ruby-talk:03118] Re: Min and max?

> Well, there's at least one point to consider with the Kernel version. Kernel
> is maybe not the right place for min since not all classes have meaningful
> comparisons. So maybe Comparable is the place (or maybe not).

I fully agree that Comparable is the right place for that. (I notice I
have an old version that doesn't support those min/max... time to upgrade)



Totally unrelated, I propose a new operation called "accum" in
Enumeration: 

[2,7,3,23,78,1,2].accum {|a,b| a.max(b)}

would return 78, the greatest element, for instance.

precondition: there is at least one element, in which case the
(degenerate) result is the element itself.

an alternate version is to provide separately with a "base" (or "seed")
value, typically the neutral element of the operation if it exists; in
that case an empty array returns the "base" value. 

more examples:

 * summing the elements in an array
 * multiplying them
 * alternating sums (using substraction as the operation)
 * factorial
 * logic: "for all ... in ... such that ..."
 * logic: "exists ... in ... such that ..."
 * compute parity, hamming code
 * one-line reimplementations of "max", "min", "member?"
 * very inefficient reimplementations of "join", "collect", "select", "reject"
 * verifying a sort

so as you see it's a very general function with a lot of uses.



Mathieu Bouchard