Starting to get over the hump

Originally published on 11 November 2009 by Jonathan Worthington.

So, a new week is here, and hopefully this will be a week of lots and lots of progress on the ng branch of Rakudo. We’ve made a pretty good start, and things are just about starting to hit the exciting stage now where we’re starting - piece by piece - to bring back the Raku setting. In there now we already have cases of operator and trait modifier definitions and well as some initial class declarations. Basically, that means that we’ve got a lot of the fundamentals in that we need for the rest of the setting. A lot of the bits we are still missing aren’t actually that hard either. In fact, it’s starting to feel like we might be getting to the point where this refactor is nearly “over the hump” and we can start winning back passing spectests quickly.

I continue to be happy with how things seem to be overall much cleaner now in the grammar and actions, as well as the general organization of the code base. My focus has been mostly on continuing to get things related to the object model and the type system back in place. Some of the highlights have been:

• Adding the augment scope modifier, which is for adding extra bits to a class definition. This is especially useful when we want to define most of a class in Raku, but need to have some of the low-level bits available in the stage 1 compiler, which we use to compile the setting. This hadn’t used to be a scope declarator, but rather a compiler-handled trait; we’ve regressed on various tests for quite a while since the spec changed, but we’ll be able to have those back when the branch lands.
• Getting multi-methods back in place again. This wasn’t too much work at all, and I’m quite happy with the end result, which no doubt does some better error detection. We use these in the setting heavily, so they - along with augment - were another big roadblock removed.
• Getting sub traits back in place, which unblocked pmichaud++ to work on export things. I’ll leave him to blog the details, but we’ve made some nice wins there, in terms of handling things better than we have before.
• Being able to pretty much copy-paste the error handling for bad type names in scoped declarators from STD.pm into Rakudo’s grammar. STD is really pretty good at giving decent diagnostics when things go wrong, and with the new grammar engine we’re being able to bring a bunch of these into Rakudo. “In my declaration, typename Monkey must be predeclared” is such a nicer error to get than the rather less informative “Malformed declaration”, which doesn’t even tell you what sort of declaration it was, let alone what was wrong with it.
• Adding back a couple of things that we were writing in PIR before but with Raku implementations this time. Strangely enough, they’re much nicer to look at. :-)

Thanks to Vienna.pm for sponsoring this work. I’m now done with catching up the Rakudo days I didn’t do in September while wandering around Asia, so now it’s into the ones I didn’t do in October. Given how much there is to do, I’m glad I’ve had a nice store of them to draw on at this point! :-)