Sat, 30 Dec 2000 09:02:55 -0800, Simon Peyton-Jones
They'll be in our first release of GHCi.
What about my old comments about distinguishing "the rest of constructors" from "contents of the constructor we found", and "the rest of fields" from "contents of the field we are considering"? IMHO the current state is wrong. Generic instances should not *require* that operations are directly propagated to arguements of constructors and values of fields. What happens when we are on the level of finding a constructor should be separated from what happens when we are looking inside its fields. And dually, combining fields should be separated from looking at the value of a field. It's simple to fix, modulo performance issues. I consider the fixed version a very good and usable solution, and the current version an unusable partially flawed design... It should be possible to rewrite classes which are derivable now to use the generic mechanism instead of ad-hockery in the compiler. Bit it will be possible only after the design is fixed not to confuse constructors and their arguments, and not to confuse sets of fields and their contents. -- __("< Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/ \__/ ^^ SYGNATURA ZASTÊPCZA QRCZAK