>>14
I don't usually use non-standard reader macros much, although I've written quite some fancy ones as exercises. The reason is because it usually makes one's code look unidiomatic and maybe even strange to someone not used to your reader macros and that macro characters themselves carry a large cost (like syntax in general does). Since it's usually possible to do almost everything(but not everything - for example fine-tweaking symbol interning behaviour without reader macros can be harder) using normal macros, I usually reach for a normal macro before I dare reach for a reader macro (and if I ever do write a reader macro, I usually have it expand into a macro or function call anyway).
The whole [_ ...] thing is actually a suggestion I saw on a certain someone's who still needs to gives us a certain CROMA Lisp's blog.
As for
cut. I have to say it looks rather cool. I may use it instead of the usual rcurry/lcurry that I tend to use for such situations. Implementing it in CL also seems reasonably simple to me, altough some slight adjustments need to be made to account for Lisp-2'ness of CL (for example
(cut <> a b) would need to be made into a
(lambda (g) (funcall g a b)), but this special treatment shouldn't be terribly hard to implement).