Based on this commit, I feel like "assert" would be a better name than "invariant-assertion". I can imagine putting these on various internal parts of a function where the self-blame would be justified. The (define id (assert ctc e)) pattern is just one common use.
Jay On Sat, May 31, 2014 at 1:46 PM, <matth...@racket-lang.org> wrote: > matthias has updated `master' from 9d94ef725e to 89dea63995. > http://git.racket-lang.org/plt/9d94ef725e..89dea63995 > > =====[ One Commit ]===================================================== > Directory summary: > 84.2% pkgs/racket-pkgs/racket-doc/scribblings/reference/ > 11.0% racket/collects/racket/contract/private/ > 4.6% racket/collects/racket/contract/ > > ~~~~~~~~~~ > > 89dea63 Matthias Felleisen <matth...@racket-lang.org> 2014-05-31 15:45 > : > | removed _contract_ language from _invariant-..._ as much as possible > | > | added a hint as to why the error message uses the inappropriate contract > language > : > M racket/collects/racket/contract/private/base.rkt | 4 ++-- > M racket/collects/racket/contract/region.rkt | 2 +- > M .../scribblings/reference/contracts.scrbl | 22 > ++++++++++---------- > > =====[ Overall Diff ]=================================================== > > pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > --- OLD/pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl > +++ NEW/pkgs/racket-pkgs/racket-doc/scribblings/reference/contracts.scrbl > @@ -1509,24 +1509,24 @@ The @racket[define-struct/contract] form only allows > a subset of the > (make-salmon #f 'pacific) > ]} > > -@defform[(invariant-contract contract-expr expr)]{ > - Establishes an invariant of @racket[expr], determined by > @racket[contract-expr]. > +@defform[(invariant-assertion invariant-expr expr)]{ > + Establishes an invariant of @racket[expr], determined by > @racket[invariant-expr]. > > - Unlike other ways to attach contracts to values, an > - @racket[invariant-contract] does not establish a boundary > - between two parties. Instead, it simply puts the contract > - on the value, treating the module containing the > - @racket[invariant-contract] expression as the party to be blamed > - for any violations of the contract. > + Unlike the specification of a contract, an > + @racket[invariant-assertion] does not establish a boundary > + between two parties. Instead, it simply attaches a logical assertion > + to the value. Because the form uses contract machinery to check the > + assertion, the surround module is treated as the party to be blamed > + for any violations of the assertion. > > - This means, for example, that the contract is checked on > + This means, for example, that the assertion is checked on > recursive calls, when an invariant is used on the right-hand > - side of a definition. > + side of a definition: > > @examples[#:eval > furlongs->feet-eval > (define furlongss->feets > - (invariant-contract > + (invariant-assertion > (-> (listof real?) (listof real?)) > (λ (l) > (cond > > racket/collects/racket/contract/private/base.rkt > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > --- OLD/racket/collects/racket/contract/private/base.rkt > +++ NEW/racket/collects/racket/contract/private/base.rkt > @@ -3,7 +3,7 @@ > (provide contract > (rename-out [-recursive-contract recursive-contract]) > current-contract-region > - invariant-contract) > + invariant-assertion) > > (require (for-syntax racket/base syntax/name syntax/srcloc) > racket/stxparam > @@ -89,7 +89,7 @@ > (procedure-rename new-val vs-name)])] > [else new-val]))) > > -(define-syntax (invariant-contract stx) > +(define-syntax (invariant-assertion stx) > (syntax-case stx () > [(_ ctc e) > (quasisyntax/loc stx > > racket/collects/racket/contract/region.rkt > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > --- OLD/racket/collects/racket/contract/region.rkt > +++ NEW/racket/collects/racket/contract/region.rkt > @@ -4,7 +4,7 @@ > define/contract > with-contract > current-contract-region > - invariant-contract) > + invariant-assertion) > > (require (for-syntax racket/base > racket/struct-info -- Jay McCarthy <j...@cs.byu.edu> Assistant Professor / Brigham Young University http://faculty.cs.byu.edu/~jay "The glory of God is Intelligence" - D&C 93 _________________________ Racket Developers list: http://lists.racket-lang.org/dev
