Re: [S29] uniq

[Damian Conway]

Luke wrote:
I wondered what uniq's default comparator should be, =:=?
&infix:<~~>
 
Woah there.  ~~ is a good comparator and all, but it's not the right
one here.  ~~ compares an object and a pattern to see if they match. 
That makes it the right choice for when and grep.  But we're trying to
remove elements that are *the same*, not elements that *match*.
Ah, I missed Larry's message last week where he mused:
    > :     3 =:= 3; # always true?
    > :     3.id ~~ 3.id; # ditto?
    >
    > I think immutable values could work that way, especially if we
    > want to store only a single representation of each immutable
    > string.
If that's now the behaviour of =:= on non-referential values, then I agree 
that C<uniq> should compare with the =:= operator.

Of course, that presupposes quite a bit of smarts on the part of the operator.
For example, we'd also need to decide what these evaluate to:
    3 =:= 3.0  # ????
    3 =:= '3'  # ????
They're surely not identical, but you'd probably want C<uniq> to think so.
Or maybe you just have to SWYM and write:
    @uniq_nums = uniq [EMAIL PROTECTED];
or:
    @uniq_strs = uniq [EMAIL PROTECTED];
if you have heterogeneous data.
Damian