> - changing evaluation order, > - implementing a data sublanguage, and > - creating new binding forms.
Thanks for the insights. But what does "data sublanguage" mean? On Sat, Nov 23, 2013 at 2:46 PM, John Clements <cleme...@brinckerhoff.org>wrote: > I'm preparing a 10-minute lightning talk on hygienic macros in rust > (preview: I'm barely going to *mention* hygiene), and in the process, I've > been surveying some of the Rust macros, and roughly categorizing them in > terms of the "three canonical categories" that Matthias > described--apologies if I'm misrepresenting him/you: > - changing evaluation order, > - implementing a data sublanguage, and > - creating new binding forms. > > Some of the Rust macros seem to fall into a fourth category, which arises > from the fact that certain things are not expressions: > > - abstracting over things that are not expressions. > > For instance: > > cmp_impl!(impl Eq, eq, ne) > cmp_impl!(impl TotalEq, equals) > cmp_impl!(impl Ord, lt, gt, le, ge) > cmp_impl!(impl TotalOrd, cmp -> cmp::Ordering) > > Each of these expands into a top-level "impl" declaration, extending > implementations of, e.g., Ord, from type T to type Ratio<T>. > > More generally, it seems to me that every time you constrain > first-class-ness by making things not-first-class (e.g. module-level stuff > in Racket), you will be required to use macros to abstract over these > things. > > Thoughts? > > Back to writing my talk... > > John > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users >
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