[ruby-talk:7253] Re: Why isn't Perl highly orthogonal?

David Alan Black <[e-mail]> wrote:
>
>Hello --
>
>On Fri, 15 Dec 2000, Ben Tilly wrote:
>
>               (map & grep)
> > In Ruby the two concepts are orthogonal.  I don't yet know
> > if you can have a function that returns different numbers
> > of elements different times.  Certainly the first thing I
> > tried to do with map was return 2 elements for 1.  (Looking
> > at a case where I know current production versions of Perl
> > doesn't scale.)  I couldn't see how to do it.  And grep
> > itself cannot be used with arbitrary blocks.  (Therefore
> > it is truer to the actual name of the function!)
>
>(I remember being relieved when I discovered find_all, after trying
>to get grep to act like Perl's grep.)
>
>As for map mapping two(or more)-for-one, I've done it, when needed,
>along these lines:
>
>[1,2,3,4,5].map do |e| [e,-e] end .flatten
>   => [1, -1, 2, -2, 3, -3, 4, -4, 5, -5]
>
I thought of that.  But if you want your output to be an
array of arrays, it doesn't work right.

Think for a second of the "array with indices" map that
someone did.  That could be as simple as

  ary.each_index.map do |i| i, ary[i] end

But my current guess is that Ruby doesn't have the
list-oriented nature of Perl, nor is there an easy way to
make it fit.  Which is a feature I will miss, but I have
to admit that simply because it was such an unusual
feature of Perl, it is rarely stressed.  Authors of books
don't realize what a unifying concept it is.  Students
don't know to look for it.  So while I find it useful, I
don't know that it fits with the principle of least
surprise.

(Yeah, I know how to imitate a list-oriented nature by
always working with through an array.  But that is a
bad hack.)

Cheers,
Ben
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