Am Mo., 22. Aug. 2022 um 00:29 Uhr schrieb Chris Hanson <xxxxxx@chris-hanson.org>:

> I’m not familiar with the term "robust unhygienic macros” and an internet
> search didn’t reveal any definitions.

The term was coined by myself for the purpose of SRFI 211.

> Is there a definition of this term, or better yet, a paper?

Unfortunately no.

What I mean by a "robust unhygienic macro" is an unhygienic macro that
even works when the unhygienic macro becomes part of the body of a
second macro expansion.

Please see "Note 2" under "Explicit-renaming macro" for an example.

> I’m a little confused because the SRFI claims that explicit-renaming macros
> can produce "robust unhygienic macros” yet syntactic-closure macros cannot.
> However, explicit-renaming is virtually identical to “reverse” syntactic-
> closure macros, which are syntactic-closure macros with the definition and use
> environments flipped.

ER macros implemented with SC (syntactic closures) are indeed not
"robust" (according to my findings). SRFI 211 describes a variation of
ER (implemented with marks & substitutions) that can be used to define
unhygienic macros that are "robust". The variation of ER is not 100%
compatible with how ER is classically implemented.

You can write down the example in Note 2 for SC as well.

Does this help?

Thanks,

Marc

PS My time this week is limited, so please excuse the rather brief reply.