Sorry to be picky: it isn't that it isn't available; it isn't allowed. It is a _good_ thing that you cannot mutate an immutable set, just like it is a good thing that (begin (set! 3 4) (+ 3 3)) doesn't evaluate to 8.
What about trying to follow with a message like this one: -> (hash-set! (hash) 'x 1) ; hash-set!: contract violation ; expected: (and/c hash? (not/c immutable?)) ; given: '#hash() ; argument position: 1st Robby On Fri, May 1, 2015 at 3:48 PM, <[email protected]> wrote: > stchang has updated `master' from 606a946212 to aef101fd84. > http://git.racket-lang.org/plt/606a946212..aef101fd84 > > =====[ One Commit ]===================================================== > Directory summary: > 100.0% racket/collects/racket/private/ > > ~~~~~~~~~~ > > aef101f Stephen Chang <[email protected]> 2015-05-01 16:43 > : > | hashset unavailable method err msg: don't say unimplemented > : > M racket/collects/racket/private/set-types.rkt | 8 ++++---- > > =====[ Overall Diff ]=================================================== > > racket/collects/racket/private/set-types.rkt > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > --- OLD/racket/collects/racket/private/set-types.rkt > +++ NEW/racket/collects/racket/private/set-types.rkt > @@ -459,13 +459,13 @@ > (define custom-set-constant > (equal-hash-code "hash code for a set based on a hash table")) > > -(define (((mk-not-impl struct-descrip) method-name) s . args) > +(define (((mk-not-impl meth-descrip struct-descrip) method-name) s . args) > (raise > (exn:fail:support > - (format "~a: method not implemented for ~a ~e" method-name > struct-descrip s) > + (format "~a: ~a operation not available for ~a: ~e" method-name > meth-descrip struct-descrip s) > (current-continuation-marks)))) > -(define mk-not-impl/immut (mk-not-impl "immutable set")) > -(define mk-not-impl/mut (mk-not-impl "mutable set")) > +(define mk-not-impl/immut (mk-not-impl "mutation" "immutable set")) > +(define mk-not-impl/mut (mk-not-impl "non-mutation" "mutable set")) > > (serializable-struct immutable-custom-set custom-set [] > #:methods gen:stream -- You received this message because you are subscribed to the Google Groups "Racket Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-dev/CAL3TdOM7fPgfmPbKXjm%2B-7m5pL5uamA%3DVNb70aYOkAfr-G_J3Q%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
