HaloO,
Damian Conway wrote:
Just a meta-point...one thing we really do need to be careful of is not
ending up with 17 different "equality" operators (like certain languages
I shall refrain from naming). So far we're contemplating:
=:=
~~
==
eq
eqv
equals
Do we really need even that many???
My opinion is there should be a role Compare that takes a
Comparer as one of it's parameters. For the above we have
in pseudo syntax e.g.:
role Object does Compare[Object, =:=]
role Num does Compare[Num, ==]
role Str does Compare[Str, eq]
::eqv ::= none(=:=); # non-Object Comparer
The difficult part is the definition of inhomogenious cases
by means of MMD unless we can form supertypes of Comparers
easily:
role Foo does Compare[Object|Num, =:= | ==]
or with set syntax and a bit de-sugared on the op:
role Foo does Compare[(Object,Num), (&infix:<=:=>, &infix:<==>)]
The driving idea here is that the syntactical choice of the programmer
amounts to a type preference of the Comparer subtype. I fully agree
that the number of standard Comparers should be kept small---that is
close to three, not counting ~~ as a Comparer but as (the only) Matcher.
--
$TSa.greeting := "HaloO"; # mind the echo!
