Re: Private classes
Hi Joachim, I used the following in the past: module M (PublicClass(..)) where class HiddenClass a class HiddenClass a = PublicClass a where ... instance HiddenClass SomeType instance PublicClass SomeType where ... Now users of M can't declare instances of PublicClass because they don't have its superclass HiddenClass in scope. Regards, Bas On Aug 17, 2013 8:10 PM, Joachim Breitner m...@joachim-breitner.de wrote: Hi, for some reason I was under the impression that if I don’t export the methods of a class, then no user of my module can create instances. But I was wrong and in fact they can; the methods will just all be bound to error Is there really no way to create a class so that no-one else can create any instances? Greetings, Joachim -- Joachim “nomeata” Breitner m...@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nome...@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nome...@debian.org ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Private classes
Hi, Am Samstag, den 17.08.2013, 20:34 +0200 schrieb Bas van Dijk: I used the following in the past: module M (PublicClass(..)) where class HiddenClass a class HiddenClass a = PublicClass a where ... ... Now users of M can't declare instances of PublicClass because they don't have its superclass HiddenClass in scope. nice idea! Unfortunately not quite what I need; I still want the user to be able to use standalone deriving instances for the class. Greetings, Joachim -- Joachim “nomeata” Breitner m...@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nome...@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nome...@debian.org signature.asc Description: This is a digitally signed message part ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Private classes
Do you mean GeneralizedNewtypeDeriving? Отправлено с iPad 17.08.2013, в 23:49, Joachim Breitner m...@joachim-breitner.de написал(а): Hi, Am Samstag, den 17.08.2013, 20:34 +0200 schrieb Bas van Dijk: I used the following in the past: module M (PublicClass(..)) where class HiddenClass a class HiddenClass a = PublicClass a where ... ... Now users of M can't declare instances of PublicClass because they don't have its superclass HiddenClass in scope. nice idea! Unfortunately not quite what I need; I still want the user to be able to use standalone deriving instances for the class. Greetings, Joachim -- Joachim “nomeata” Breitner m...@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nome...@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nome...@debian.org ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Private classes
My usual variant of this is to use class Foo' a class Foo' a = Foo a instance Foo' a = Foo a and not export Foo' Sent from my iPhone On Aug 17, 2013, at 2:34 PM, Bas van Dijk v.dijk@gmail.com wrote: Hi Joachim, I used the following in the past: module M (PublicClass(..)) where class HiddenClass a class HiddenClass a = PublicClass a where ... instance HiddenClass SomeType instance PublicClass SomeType where ... Now users of M can't declare instances of PublicClass because they don't have its superclass HiddenClass in scope. Regards, Bas On Aug 17, 2013 8:10 PM, Joachim Breitner m...@joachim-breitner.de wrote: Hi, for some reason I was under the impression that if I don’t export the methods of a class, then no user of my module can create instances. But I was wrong and in fact they can; the methods will just all be bound to error Is there really no way to create a class so that no-one else can create any instances? Greetings, Joachim -- Joachim “nomeata” Breitner m...@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nome...@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nome...@debian.org ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Private classes
If you don't export the methods but do use DefaultSignatures for them in terms of a GHC.Generics version of the class that also works in many cases. Sent from my iPhone On Aug 17, 2013, at 2:08 PM, Joachim Breitner m...@joachim-breitner.de wrote: Hi, for some reason I was under the impression that if I don’t export the methods of a class, then no user of my module can create instances. But I was wrong and in fact they can; the methods will just all be bound to error Is there really no way to create a class so that no-one else can create any instances? Greetings, Joachim -- Joachim “nomeata” Breitner m...@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nome...@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nome...@debian.org ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
