On Aug 13, 2011, at 10:44 AM, John Clements wrote: > > Adding dev to followups, hope that's okay with all three of you. > > On Aug 12, 2011, at 7:15 PM, Eli Barzilay wrote: > >> A few seconds ago, Matthias Felleisen wrote: >>> >>> This sounds wrong. The only way there can be a dependency is via >>> require. So how can it not be checkable, never mind copy or >>> hand-coding. >> >> The stepper has some function that annotates syntaxes with a stepper >> specific value. Stephen wanted to use this function but couldn't >> because there was a dependency cycle. So to "resolve" it, he copied >> the function into `racket/private/promise' -- so now there's a bit of >> stepper code that is duplicated in the core. The duplication is >> obvious problem #1. The more subtle problem is the existence of code >> in the core that has no meaning without the stepper. > > I'm coming a bit late to this party, but I disagree with at least some of > this. > > Actually, I want to disagree mostly with the "more subtle problem." > > To start with, here's the basic motivating change to the code (lots like > this): > > - (defsubst (~and x ...) (~ (and (! x) ...)) ~and *and) > + (defsubst (~and x ...) (hidden-~ (and (hidden-! x) ...)) ~and *and)
One more minor aside I should have mentioned: Stephen's use of a macro here reads *much more nicely* than the way the rest of the stepper annotations explicitly inject the annotations using with-syntax; when I get time, I want to adopt this approach elsewhere. Nice! John
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