Thanks for the feedback! Some of these were not concerns for my use case, so I’ll do a bit more design before submitting something.
-- Sent from my phoneamajig > On Oct 30, 2020, at 12:36, George Neuner <gneun...@comcast.net> wrote: > > >> On 10/30/2020 3:08 PM, William J. Bowman wrote: >> Let me aid this discussion by copying in the ~10 lintes of code in question: >> >> > (define-syntax (dictof syn) >> > (syntax-parse syn >> > [(_ (k:id pred?) ...) >> > (quasisyntax/loc syn >> > (dictof/proc `((k . ,pred?) ...)))])) >> > > (define ((dictof/proc spec) h) >> > (and (eq? (dict-keys h) (dict-keys spec)) >> > (for/and ([(k pred?) (in-dict spec)]) >> > (pred? (dict-ref h k))))) >> >> The macro is merely a syntactic transformation to 1 line of code that >> implements >> the functionality of the contract at run-time. >> Is there some reason to avoid macros in this particular case? > > There's rarely any problem with macros that only provide syntactic sugar. > > The issues wrt contracts are how heavy are the dictionary functions. The FOR > loop is concerning because the check time is proportional to the size of the > dictionary [again recalling that contracts live on in release code]. > > For performance it would be better to enforce the predicate on values as they > are entered, and then assume anything already in the dictionary is correct. > It is sensible to provide a function that validates the whole dictionary, but > I would make it something the programmer has to invoke deliberately rather > than a contract to be enforced at (even just 1st in module) mention of the > dictionary. > > YMMV, > George > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/95997336-33d4-5c5b-b329-9ea691fe59ef%40comcast.net. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/E9A25DEF-7B1B-426C-AFAD-319C5C2E9757%40williamjbowman.com.
