RE: [racket-users] namespace-undefine-variable! question
Hi Jens Axel That's a very clear answer. Thanks. I don't know why procedures acting on namespaces treat directly imported identifiers differently than imported identifiers.May be there is a reason, but don't bother, Of cource it is always nice to know how things work, but in the present case I am happy to know how to handle the map? argument, even without knowing the reason the inclusion of a map? argument in a number of functions actnig on namespaces. I am sure it can be useful in some cases, but I never have encountered those cases. Of course +1 to the idea of adding a map? argument to namespace-undefine- variable!. Thanks again, Jos _ From: jensaxelsoega...@gmail.com [mailto:jensaxelsoega...@gmail.com] On Behalf Of Jens Axel Søgaard Sent: viernes, 28 de agosto de 2015 13:48 To: Jos Koot Cc: Racket-Users List Subject: Re: [racket-users] namespace-undefine-variable! question As far as I can tell a namespace knows if an identifier is defined directly in the module or if it is imported. If map? is #t then, imported identifiers are handled - and if map? is #f then only identifiers defined directly in the module is handled. Since namespace-undefined-variable! has no map? argument, you can't undefine imported variables. Why the map? argument is missing from namespace-undefined-variable! I don't know /Jens Axel 2015-08-27 19:24 GMT+02:00 Jos Koot jos.k...@gmail.com: Thanks for your prompt and clear reply. I admit I don't fully understand the map? argument. Just by trying out I know that for my purposes I always have to provide true for the map? argument. Meanwhile I insert the namespace-set-variable-value! line with true map? argument, as you suggest. Thanks again, Jos _ From: jensaxelsoega...@gmail.com [mailto:jensaxelsoega...@gmail.com] On Behalf Of Jens Axel Søgaard Sent: jueves, 27 de agosto de 2015 17:35 To: Jos Koot Cc: Racket-Users List Subject: Re: [racket-users] namespace-undefine-variable! question The issue here is whether the namespance's identifier mapping is used or not. The documentation for namespace-undefine-variable! says: Removes the sym variable, if any, in the top-level environment of namespace in its base phase. The namespace’s identifier mapping (see Namespaces) is unaffected. We can see that list is use the identifier mapping by changing the second argument of namespace-variable-value to #f. #lang racket (define ns (make-base-namespace)) (namespace-variable-value 'list #f (λ () 'not-found) ns) which evaluates to 'not-found. Inserting your own non-imported value for list makes the identifier non- imported and has the happy side-effect of making namespace-undefined-variable! capable of removing the binding from namespace. In some sense namespace-undefined-variable! miss an map? argument. Your solution: insert, then undefine seem to be the best solution for now. /Jens Axel you n 2015-08-27 16:53 GMT+02:00 Jos Koot jos.k...@gmail.com: The following works: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:print-syntax-width #;3 (namespace-set-variable-value! 'list 'whatever (λ () #f) ns) #;4 (namespace-undefine-variable! 'list ns) #;5 (namespace-variable-value 'list#t (λ () 'not-found) ns) ; - not-found But when I omit line 3 it does not work: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:list #;4 (namespace-undefine-variable! 'list ns) ;- error namespace-undefine-variable!: given name is not defined ; name: list This I did with: Welcome to DrRacket, version 6.2.0.5--2015-07- 06(d6fa581/a) [3m]. Code in the definitions window. The problem is not typical for 'list only. The same happens with (at least some) other variables of a base-namespace. I have no clue why commenting out line 3 gives an error. Do I misinterpret the docs on namespaces? Thanks, Jos PS I use a base-namespace in a toy interpreter. It allows me to easily borrow all variables from a base-namespace. But some of them I want to undefine. -- 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. -- -- Jens Axel Søgaard -- -- Jens Axel Søgaard -- 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.
Re: [racket-users] namespace-undefine-variable! question
The issue here is whether the namespance's identifier mapping is used or not. The documentation for namespace-undefine-variable! says: Removes the sym variable, if any, in the top-level environment of namespace in its base phase file:///Applications/Racket%20v6.2/doc/reference/syntax-model.html?q=namespace-va#%28tech._base._phase%29. The namespace’s identifier file:///Applications/Racket%20v6.2/doc/reference/syntax-model.html?q=namespace-va#%28tech._identifier%29 mapping (see Namespaces file:///Applications/Racket%20v6.2/doc/reference/syntax-model.html?q=namespace-va#%28part._namespace-model%29) is unaffected. We can see that list is use the identifier mapping by changing the second argument of namespace-variable-value to #f. #lang racket (define ns (make-base-namespace)) (namespace-variable-value 'list #f (λ () 'not-found) ns) which evaluates to 'not-found. Inserting your own non-imported value for list makes the identifier non-imported and has the happy side-effect of making namespace-undefined-variable! capable of removing the binding from namespace. In some sense namespace-undefined-variable! miss an map? argument. Your solution: insert, then undefine seem to be the best solution for now. /Jens Axel you n 2015-08-27 16:53 GMT+02:00 Jos Koot jos.k...@gmail.com: The following works: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:print-syntax-width #;3 (namespace-set-variable-value! 'list 'whatever (λ () #f) ns) #;4 (namespace-undefine-variable! 'list ns) #;5 (namespace-variable-value 'list#t (λ () 'not-found) ns) ; - not-found But when I omit line 3 it does not work: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:list #;4 (namespace-undefine-variable! 'list ns) ;- error namespace-undefine-variable!: given name is not defined ; name: list This I did with: Welcome to DrRacket, version 6.2.0.5--2015-07-06(d6fa581/a) [3m]. Code in the definitions window. The problem is not typical for 'list only. The same happens with (at least some) other variables of a base-namespace. I have no clue why commenting out line 3 gives an error. Do I misinterpret the docs on namespaces? Thanks, Jos PS I use a base-namespace in a toy interpreter. It allows me to easily borrow all variables from a base-namespace. But some of them I want to undefine. -- 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. -- -- Jens Axel Søgaard -- 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.
RE: [racket-users] namespace-undefine-variable! question
Thanks for your prompt and clear reply. I admit I don't fully understand the map? argument. Just by trying out I know that for my purposes I always have to provide true for the map? argument. Meanwhile I insert the namespace-set-variable-value! line with true map? argument, as you suggest. Thanks again, Jos _ From: jensaxelsoega...@gmail.com [mailto:jensaxelsoega...@gmail.com] On Behalf Of Jens Axel Søgaard Sent: jueves, 27 de agosto de 2015 17:35 To: Jos Koot Cc: Racket-Users List Subject: Re: [racket-users] namespace-undefine-variable! question The issue here is whether the namespance's identifier mapping is used or not. The documentation for namespace-undefine-variable! says: Removes the sym variable, if any, in the top-level environment of namespace in its file:///Applications/Racket%20v6.2/doc/reference/syntax- model.html?q=namespace-va#%28tech._base._phase%29 base phase. The namespace’s file:///Applications/Racket%20v6.2/doc/reference/syntax- model.html?q=namespace-va#%28tech._identifier%29 identifier mapping (see Namespaces file:///Applications/Racket%20v6.2/doc/reference/syntax- model.html?q=namespace-va#%28part._namespace-model%29 ) is unaffected. We can see that list is use the identifier mapping by changing the second argument of namespace-variable-value to #f. #lang racket (define ns (make-base-namespace)) (namespace-variable-value 'list #f (λ () 'not-found) ns) which evaluates to 'not-found. Inserting your own non-imported value for list makes the identifier non- imported and has the happy side-effect of making namespace-undefined-variable! capable of removing the binding from namespace. In some sense namespace-undefined-variable! miss an map? argument. Your solution: insert, then undefine seem to be the best solution for now. /Jens Axel you n 2015-08-27 16:53 GMT+02:00 Jos Koot jos.k...@gmail.com: The following works: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:print-syntax-width #;3 (namespace-set-variable-value! 'list 'whatever (λ () #f) ns) #;4 (namespace-undefine-variable! 'list ns) #;5 (namespace-variable-value 'list#t (λ () 'not-found) ns) ; - not-found But when I omit line 3 it does not work: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:list #;4 (namespace-undefine-variable! 'list ns) ;- error namespace-undefine-variable!: given name is not defined ; name: list This I did with: Welcome to DrRacket, version 6.2.0.5--2015-07- 06(d6fa581/a) [3m]. Code in the definitions window. The problem is not typical for 'list only. The same happens with (at least some) other variables of a base-namespace. I have no clue why commenting out line 3 gives an error. Do I misinterpret the docs on namespaces? Thanks, Jos PS I use a base-namespace in a toy interpreter. It allows me to easily borrow all variables from a base-namespace. But some of them I want to undefine. -- 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. -- -- Jens Axel Søgaard -- 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.
Re: [racket-users] namespace-undefine-variable! question
Hi Jos, But some of them I want to undefine. Isn't it easier to make your own restricted #lang and then use make-module-evaluator? Sorry to butt in. Deren On Thu, Aug 27, 2015 at 1:24 PM, Jos Koot jos.k...@gmail.com wrote: Thanks for your prompt and clear reply. I admit I don't fully understand the map? argument. Just by trying out I know that for my purposes I always have to provide true for the map? argument. Meanwhile I insert the namespace-set-variable-value! line with true map? argument, as you suggest. Thanks again, Jos -- *From:* jensaxelsoega...@gmail.com [mailto:jensaxelsoega...@gmail.com] *On Behalf Of *Jens Axel Søgaard *Sent:* jueves, 27 de agosto de 2015 17:35 *To:* Jos Koot *Cc:* Racket-Users List *Subject:* Re: [racket-users] namespace-undefine-variable! question The issue here is whether the namespance's identifier mapping is used or not. The documentation for namespace-undefine-variable! says: Removes the sym variable, if any, in the top-level environment of namespace in its base phase. The namespace’s identifier mapping (see Namespaces) is unaffected. We can see that list is use the identifier mapping by changing the second argument of namespace-variable-value to #f. #lang racket (define ns (make-base-namespace)) (namespace-variable-value 'list #f (λ () 'not-found) ns) which evaluates to 'not-found. Inserting your own non-imported value for list makes the identifier non-imported and has the happy side-effect of making namespace-undefined-variable! capable of removing the binding from namespace. In some sense namespace-undefined-variable! miss an map? argument. Your solution: insert, then undefine seem to be the best solution for now. /Jens Axel you n 2015-08-27 16:53 GMT+02:00 Jos Koot jos.k...@gmail.com: The following works: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:print-syntax-width #;3 (namespace-set-variable-value! 'list 'whatever (λ () #f) ns) #;4 (namespace-undefine-variable! 'list ns) #;5 (namespace-variable-value 'list#t (λ () 'not-found) ns) ; - not-found But when I omit line 3 it does not work: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:list #;4 (namespace-undefine-variable! 'list ns) ;- error namespace-undefine-variable!: given name is not defined ; name: list This I did with: Welcome to DrRacket, version 6.2.0.5--2015-07-06(d6fa581/a) [3m]. Code in the definitions window. The problem is not typical for 'list only. The same happens with (at least some) other variables of a base-namespace. I have no clue why commenting out line 3 gives an error. Do I misinterpret the docs on namespaces? Thanks, Jos PS I use a base-namespace in a toy interpreter. It allows me to easily borrow all variables from a base-namespace. But some of them I want to undefine. -- 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. -- -- Jens Axel Søgaard -- 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.
[racket-users] namespace-undefine-variable! question
The following works: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:print-syntax-width #;3 (namespace-set-variable-value! 'list 'whatever (λ () #f) ns) #;4 (namespace-undefine-variable! 'list ns) #;5 (namespace-variable-value 'list#t (λ () 'not-found) ns) ; - not-found But when I omit line 3 it does not work: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:list #;4 (namespace-undefine-variable! 'list ns) ;- error namespace-undefine-variable!: given name is not defined ; name: list This I did with: Welcome to DrRacket, version 6.2.0.5--2015-07-06(d6fa581/a) [3m]. Code in the definitions window. The problem is not typical for 'list only. The same happens with (at least some) other variables of a base-namespace. I have no clue why commenting out line 3 gives an error. Do I misinterpret the docs on namespaces? Thanks, Jos PS I use a base-namespace in a toy interpreter. It allows me to easily borrow all variables from a base-namespace. But some of them I want to undefine. -- 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.
RE: [racket-users] namespace-undefine-variable! question
Of course there are easier methods, yours included. (I used the method of defining a new language years ago to implement a lazy lambda-calculus, it should be in the archives of this user's list) What I now have is a toy meta-circular interpreter consisting of one single symbolic expression acceptable to both racket/base and the interpreter itself, using racket/base as bootstrap. My toy language does not include define-forms.(it does include multiple values and makes no distinction between syntactic and variable bindings; it has some crude tools to define new hygienic macros; It includes a curry-option that automatically curries procedure calls and even syntactic forms; I am working on a version that includes a lazy-option, even for for the expr in (set! var expr)) I have tested the metacircularity to 5 levels deep. Earlier experience has shown me that an interpreter may seem metacircular to some levels but then fails at one level deeper. My interpreter includes a trace option (something like debug in DrRacket, but much simpler and simply printing the process of evaluation). For this trace-option I need the same parameter for all levels of meta-circularity, or otherwise the trace-option can enter an infinite printing loop (for example when tracing a printer procedure attached as prop:custom-write to a struct-type). Therefore I use a parameter from a base-namespace that allows disabling tracing at all levels of metacircularity, but have to hide it from the user. That's why I want to undefine some variables of the base- namespace I use to borrow variables crom racket/base. Of cource I could use a parameter defined outside the interpreter itself, but I want my interpreter to be written within the intersection of its own language and racket/base. I don't want my interpreter to depend on a parameter defined outside the interpreter itself, for in this way the interpreter would not realy be metacircular. I also want my interpreter to correctly handle syntaxes and procedures coming from a dictinct instance of the module that defines the interpreter. Therefore it is important that I import a parameter from a base-namespace for disabling tracing. (it remains possible to fool my interpreter, though) As I said, it is just a toy and certainly has no value as a languag for real life programs. In addition, my interpreter does not obey the principle of the distinction between expansion, compilation and run-time phases of Racket. A key principle in my interprreter is that tthere is no distinction between expansion and run time: the name of a syntacic form is bound as a variable during the evaluation. This may be very wrong, but I am just playing around. Thanks for your comment, Jos _ From: Deren Dohoda [mailto:deren.doh...@gmail.com] Sent: jueves, 27 de agosto de 2015 20:19 To: Jos Koot Cc: Jens Axel Søgaard; Racket-Users List Subject: Re: [racket-users] namespace-undefine-variable! question Hi Jos, But some of them I want to undefine. Isn't it easier to make your own restricted #lang and then use make-module- evaluator? Sorry to butt in. Deren On Thu, Aug 27, 2015 at 1:24 PM, Jos Koot jos.k...@gmail.com wrote: Thanks for your prompt and clear reply. I admit I don't fully understand the map? argument. Just by trying out I know that for my purposes I always have to provide true for the map? argument. Meanwhile I insert the namespace-set-variable-value! line with true map? argument, as you suggest. Thanks again, Jos _ From: jensaxelsoega...@gmail.com [mailto:jensaxelsoega...@gmail.com] On Behalf Of Jens Axel Søgaard Sent: jueves, 27 de agosto de 2015 17:35 To: Jos Koot Cc: Racket-Users List Subject: Re: [racket-users] namespace-undefine-variable! question The issue here is whether the namespance's identifier mapping is used or not. The documentation for namespace-undefine-variable! says: Removes the sym variable, if any, in the top-level environment of namespace in its base phase. The namespace’s identifier mapping (see Namespaces) is unaffected. We can see that list is use the identifier mapping by changing the second argument of namespace-variable-value to #f. #lang racket (define ns (make-base-namespace)) (namespace-variable-value 'list #f (λ () 'not-found) ns) which evaluates to 'not-found. Inserting your own non-imported value for list makes the identifier non- imported and has the happy side-effect of making namespace-undefined-variable! capable of removing the binding from namespace. In some sense namespace-undefined-variable! miss an map? argument. Your solution: insert, then undefine seem to be the best solution for now. /Jens Axel you n 2015-08-27 16:53 GMT+02:00 Jos Koot jos.k...@gmail.com: The following works: #lang racket/base #;1 (define ns (make-base-namespace)) #;2 (namespace-variable-value 'list #t (λ () 'not-found) ns) ; - #procedure:print-syntax-width #;3 (namespace-set-variable-value! 'list 'whatever (λ
