ashley at semantic.org
Fri Jul 24 19:28:30 EDT 2009
On Fri, 2009-07-24 at 12:13 +0100, Jules Bean wrote:
> When this actually alters the integer inside my Micro, I'm going to be
> pretty surprised.
> Or maybe I'm not that surprised, but the point is, it exposes the
> internals of Fixed. It's an abstraction hole.
The whole point of SYB is to break abstraction. A "subterm" is a rather
vague concept, and it makes a rather arbitrary distinction between
"loosely holding" the contained value (will be touched by 'everywhere')
and "tightly using" it (won't be touched).
Does Complex hold or use its real and imaginary parts? Does Ratio hold
or use its numerator and denominator? In both cases, the whole means
something more than the aggregate of its parts, but this is typically
the case with data-types. If you want a data-type that means nothing
more than "aggregate", us (,) tuples.
Generally I recommend KYB if you care about abstraction, because YB is
actually meaningful code that should not be Sd.
More information about the Libraries