(Interned) symbols that have the same printed form but are not equal to each other already exist tho; the symbols produced by string->unreadable-symbol are not equal? to their counterparts produced by the reader, but nevertheless have the same printed representation.
Shu-Hung On Wed, Dec 27, 2017 at 9:26 PM, 'John Clements' via Racket Users <racket-users@googlegroups.com> wrote: > > >> On Dec 27, 2017, at 19:06, Jay McCarthy <jay.mccar...@gmail.com> wrote: >> >> This seems to be consistent with my Web browser and editor. Are the >> symbols eq? or equal? > > Neither. Am I misunderstanding you? Here’s code: > > #lang racket > > (define bad-symbol (string->symbol "\uFEFFhello")) > > (define regular-symbol 'hello) > > bad-symbol > regular-symbol > (equal? bad-symbol regular-symbol) > (eq? bad-symbol regular-symbol) > > this evaluates in DrR to: > > Welcome to DrRacket, version 6.11.0.5--2017-12-20(-/f) [3m]. > Language: racket, with debugging; memory limit: 4096 MB. > 'hello > 'hello > #f > #f >> > > If you copy and paste these from the interactions into the definitions > window, you can even get this: > > #lang racket > > (equal? 'hello 'hello) > (eq? 'hello ‘hello) > > evaluates to: > > Welcome to DrRacket, version 6.11.0.5--2017-12-20(-/f) [3m]. > Language: racket, with debugging; memory limit: 4096 MB. > #f > #f >> > > Did you misunderstand me, or did I misunderstand you? > > John > > > > > >> > >> On Wed, Dec 27, 2017 at 3:54 PM, 'John Clements' via Racket Users >> <racket-users@googlegroups.com> wrote: >>> I was working with files containing a Byte Order Mark today, and in the >>> process of writing a test case, I discovered that >>> >>> (string->symbol “\uFEFF”) >>> >>> produces a symbol whose printed representation is >>> >>> ‘hello >>> >>> … which seems unfortunate; I guess I would have expected something like >>> >>> ‘|\uFEFFhello| >>> >>> (… although I see now that this kind of escaping is not currently enabled >>> inside vertical bars). >>> >>> This leads to situations where two symbols with the same printed >>> representation may not be equal?, which seems unfortunate. >>> >>> Am I overlooking a good reason why this is the desired behavior? >>> >>> John >>> >>> >>> >>> -- >>> 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. >>> For more options, visit https://groups.google.com/d/optout. >> >> >> >> -- >> -=[ Jay McCarthy http://jeapostrophe.github.io ]=- >> -=[ Associate Professor PLT @ CS @ UMass Lowell ]=- >> -=[ Moses 1:33: And worlds without number have I created; ]=- >> >> -- >> 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. >> For more options, visit https://groups.google.com/d/optout. > > > > -- > 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. > For more options, visit https://groups.google.com/d/optout. -- 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. For more options, visit https://groups.google.com/d/optout.
