On Fri, Aug 12, 2011 at 1:58 PM, Ryan Culpepper <r...@cs.utah.edu> wrote: > On 08/12/2011 11:37 AM, Sam Tobin-Hochstadt wrote: >> >> On Fri, Aug 12, 2011 at 1:25 PM, Danny Yoo<d...@cs.wpi.edu> wrote: >>> >>> In which the first three lines are coming from compile-time, and I see >>> that my lift-to-toplevel macro is firing off, even though I placed it >>> in the stop-list of local-expand. >> >> What's happening here is that the `#%module-begin' binding from >> `racket/base' calls `local-expand' on each of its forms, to determine >> whether its an expression or not. This implements the printing of >> top-level expressions. If you replace `#%module-begin' with >> `#%plain-module-begin', you should see the desired behavior. > > '#%plain-module-begin' also calls 'local-expand' to expose definitions, > requires, etc. When I change Danny's sample code to use > '#%plain-module-begin' instead of '#%module-begin', I get the same output.
`#%plain-module-begin' doesn't seem to explicitly call `local-expand', in the sense that the Macro Stepper shows. For example, this program: (module m racket (#%plain-module-begin (#%expression 3) 4)) when macro-stepped, shows no local-expand steps, but this program: (module m racket (#%module-begin (#%expression 3) 4)) does show local-expansion steps. > In general, when a 'local-expand' happens inside of another 'local-expand', > the outer stop list is discarded. Since '#%plain-module-begin' effectively > calls 'local-expand', I would expect the #'lift-to-toplevel stop list to > never have any effect. That's not quite true. This program shows the difference between having it in the stop-list and not: (module e 'small-lang (printf "hello world\n") (#%expression (lift-to-toplevel (printf "ok!")))) In general, if `lift-to-toplevel' is an expression form, then I'd do (define-syntax-rule (lift-to-toplevel-aux . rest) (#%expression (lift-to-toplevel . rest))) Which I think would fix the problem (even for `racket/base's `#%module-begin'). If it needs to be a top-level form, more tricks are needed. -- sam th sa...@ccs.neu.edu _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
