Re: [racket-dev] cross-phase syntax constants
I find the example too abstract to understand why the computation happens at the wrong phase when you adjust the code with `begin-for-syntax'. Can you explain a little more, maybe with a more concrete example? Just in case, here's the code that I think you have in mind for wrong phase: #lang racket/load (module m1 racket (define l (list #'l)) (provide l)) (module m2 racket (require (for-syntax 'm1)) (define-syntax (mac stx) #`(begin-for-syntax (module* sub #f (length (list #,(car l)) (provide mac)) (module m3 racket (require 'm2) (mac)) (require (submod 'm3 sub)) At Thu, 5 Jul 2012 17:17:08 -0400, Sam Tobin-Hochstadt wrote: I'd like to write a program basically like this: #lang racket/load (module m1 racket (define l (list #'l)) (provide l)) (module m2 racket (require (for-syntax 'm1)) (define-syntax (mac stx) #`(module* sub #f (length (list #,(car l) (provide mac)) (module m3 racket (require 'm2) (mac)) But I can't come up with any way to `require` m1 appropriately so that `l` is bound in the generated submodule. If I wrap the body of the submodule in `begin-for-syntax`, then it works, but then loading the submodule does the computation at the wrong phase. So another solution would be `dynamic-require-for-template`, if that's feasible. -- sam th sa...@ccs.neu.edu _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] cross-phase syntax constants
On Fri, Jul 6, 2012 at 11:00 AM, Matthew Flatt mfl...@cs.utah.edu wrote: I find the example too abstract to understand why the computation happens at the wrong phase when you adjust the code with `begin-for-syntax'. Can you explain a little more, maybe with a more concrete example? Just in case, here's the code that I think you have in mind for wrong phase: I had not realized that I could sensibly wrap a module in a `begin-for-syntax`. What is the semantic difference between that and a plain submodule (other than my example working)? I will try that, and see if it works for my purposes. At Thu, 5 Jul 2012 17:17:08 -0400, Sam Tobin-Hochstadt wrote: I'd like to write a program basically like this: #lang racket/load (module m1 racket (define l (list #'l)) (provide l)) (module m2 racket (require (for-syntax 'm1)) (define-syntax (mac stx) #`(module* sub #f (length (list #,(car l) (provide mac)) (module m3 racket (require 'm2) (mac)) But I can't come up with any way to `require` m1 appropriately so that `l` is bound in the generated submodule. If I wrap the body of the submodule in `begin-for-syntax`, then it works, but then loading the submodule does the computation at the wrong phase. So another solution would be `dynamic-require-for-template`, if that's feasible. -- sam th sa...@ccs.neu.edu -- sam th sa...@ccs.neu.edu _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] cross-phase syntax constants
At Fri, 6 Jul 2012 11:13:44 -0400, Sam Tobin-Hochstadt wrote: I had not realized that I could sensibly wrap a module in a `begin-for-syntax`. What is the semantic difference between that and a plain submodule (other than my example working)? For `(module* _name #f )', `begin-for-syntax' shifts the phase level of the enclosing module's bindings relative to the submodule. An enclosing `begin-for-syntax' has no effect on a `module' submodule or `module*' with a module path instead of `#f', though. (This is documented with `module*'.) _ Racket Developers list: http://lists.racket-lang.org/dev
[racket-dev] cross-phase syntax constants
I'd like to write a program basically like this: #lang racket/load (module m1 racket (define l (list #'l)) (provide l)) (module m2 racket (require (for-syntax 'm1)) (define-syntax (mac stx) #`(module* sub #f (length (list #,(car l) (provide mac)) (module m3 racket (require 'm2) (mac)) But I can't come up with any way to `require` m1 appropriately so that `l` is bound in the generated submodule. If I wrap the body of the submodule in `begin-for-syntax`, then it works, but then loading the submodule does the computation at the wrong phase. So another solution would be `dynamic-require-for-template`, if that's feasible. -- sam th sa...@ccs.neu.edu _ Racket Developers list: http://lists.racket-lang.org/dev
