August 2013 - Pharo-dev - lists.pharo.org

Re: [Pharo-dev] Smalltalk = strongly typed

by Alain Plantec

Hi Ben, Thanks for the references, I've also found this post interesting: http://blogs.perl.org/users/ovid/2010/08/what-to-know-before-debating-type-… Cheers Alain On 2 aoÃ»t 2013, at 06:03, btc(a)openinworld.com wrote: > greetings all, > > I'm in the final weeks of writing up my Masters dissertation and seeking some scholarly references to Smalltalk being "Strongly Typed." > > I my review of Smalltalk I was surprised to find that [1] describes Smalltalk as Strongly Typed, since Smalltalk is sometimes denigrated as being untyped / weakly typed. From reviewing discussion forums this now makes sense, but I can only find one of scholarly reference that briefly mentions this [2]. The most enlightening is [3] which defines Type Strength as: > > "A strongly typed language prevents any operation on the wrong type of data. In weakly typed languages there are ways to escape this restriction: type conversions" > > meaning that getting a MNU is a form of Strong Typing since you can't make a Smalltalk object run a method that is not its own. The problem appears to be that Strong Typing has been synonymous with Static Typing for a long time, and Static Typing strongly ties types to variables, except in Dynamically Typed languages, I think types can be considered independently from variables, in which case the definition of [3] has some merit, hence Smalltalk is Strongly Typed. > > Sounds controversial, so I'm just hoping for some peer reviewed backup - but only you have something easily to hand. This is just a small thing I can just leave out if necessary. > > cheers -ben > > [1] http://www.squeak.org/Features/ > [2] p15, http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.35.7507&rep=rep1&t… > [3] http://www.cs.kuleuven.ac.be/publicaties/rapporten/cw/CW415.pdf >

Aug. 2, 2013

drawReverseFrame: is strange because it does not use self

by StÃ©phane Ducasse

Rectangle>>drawReverseFrame: rect Display border: rect width: 2 rule: Form reverse fillColor: Color gray and force user to create a dummy rectangle to invoke it. Stef

Aug. 2, 2013

Why we should run SmallLint

by StÃ©phane Ducasse

convertFromCompoundText | readStream converter | readStream := self readStream. ^ self class new: self size streamContents: [ :writeStream| converter := CompoundTextConverter new. converter ifNil: [^ self]. [readStream atEnd] whileFalse: [ writeStream nextPut: (converter nextFromStream: readStream)]]. CompoundTextConverter new -> DNU convertFromSystemString | readStream converter | readStream := self readStream. ^ self class new: self size streamContents: [ :writeStream| converter := LanguageEnvironment defaultSystemConverter. converter ifNil: [^ self]. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [readStream atEnd] whileFalse: [ writeStream nextPut: (converter nextFromStream: readStream)]]. systemConverterClass self subclassResponsibility. ^ Latin1TextConverter. What!!!! Stef

Aug. 2, 2013

Re: [Pharo-dev] Smalltalk = strongly typed

by Enrico Schwass

Hello If people ask me about Smalltalk I soon refer to the term duck typing. It perfectly fits. Enno On 02.08.2013, at 20:55, Igor Stasenko <siguctua(a)gmail.com> wrote: > I wonder if 'types' can be applied to smalltalk at all. > Saying it is 'unityped' language (since everything is an object) is > same as saying it has no types. > > Because where you need types? When you want to manipulate with data, > but in smalltalk all > data manipulation semantics is provided and implemented at primitive > level, but not by the language itself. > At language level the only semantics which is defined is message > passing, closures, > return and assignment. > > There is no any rule(s), in smalltalk at language level, saying that > result of expression: > > 1 + 2 > > should be of integer type. Because this is provided by implementation > but not defined by language itself e.g.: > it is just a method in corresponding class, which implemented in such > a way that result of expression will be instance of Integer (or > SmallInteger to be precise). > Now, if you change implementation so result will be float (or anything > else), will such change allow you to say, that it is no longer > smalltalk, or that now it is weakly typed or "anything-else typed"? > > Because smalltalk code do not operates directly with data, but only > with references to it (which is objects). > > Take an assignment, for example. > In staticly-typed language assignment copies the value of expression > to variable, e.g.: > > a = 10 > > "now variable a has value = 10" > > in smalltalk, assignment is not copying value, but changing the reference: > > a := 10 > > "now variable a points (or refers) to object '10'" > > and thus, whatever 'type' used to represent the integer value 10 is > completely irrelevant > for assignment operation. > > -- > Best regards, > Igor Stasenko. >

Aug. 2, 2013

Re: [Pharo-dev] Smalltalk = strongly typed

by Igor Stasenko

I wonder if 'types' can be applied to smalltalk at all. Saying it is 'unityped' language (since everything is an object) is same as saying it has no types. Because where you need types? When you want to manipulate with data, but in smalltalk all data manipulation semantics is provided and implemented at primitive level, but not by the language itself. At language level the only semantics which is defined is message passing, closures, return and assignment. There is no any rule(s), in smalltalk at language level, saying that result of expression: 1 + 2 should be of integer type. Because this is provided by implementation but not defined by language itself e.g.: it is just a method in corresponding class, which implemented in such a way that result of expression will be instance of Integer (or SmallInteger to be precise). Now, if you change implementation so result will be float (or anything else), will such change allow you to say, that it is no longer smalltalk, or that now it is weakly typed or "anything-else typed"? Because smalltalk code do not operates directly with data, but only with references to it (which is objects). Take an assignment, for example. In staticly-typed language assignment copies the value of expression to variable, e.g.: a = 10 "now variable a has value = 10" in smalltalk, assignment is not copying value, but changing the reference: a := 10 "now variable a points (or refers) to object '10'" and thus, whatever 'type' used to represent the integer value 10 is completely irrelevant for assignment operation. -- Best regards, Igor Stasenko.

Aug. 2, 2013

Re: [Pharo-dev] Smalltalk = strongly typed

by kilon

I dont see the reason for the confusion. Static typed language is a language that defines the type of the variable at the creating of the variable. Strongly typed language is a language that wont automatically convert the type of a variable if the correct type is not used. Dynamic typed language use types but variable can change types depending on the type of data it receives. Weakly typed language will convert the type automatically if the wrong type is used. There is nothing stopping a static type language being weakly typed. Actually javascript is such an example. I have no idea how one could mix up static typing with strong typing , they look similar as word but they semantics if you exclude the fact that both talk about types are vastly different. In case of smalltalk none of the above is valid because smalltalk does not use types but rather objects. At best you could say it uses objects that emulate types, but since the object itself is typeless I dont think it makes a difference. Because of this its possible to emulate all these characteristic at the same time since the nature of smalltalk is to be very flexible. Probably lisp is very similar too. Afterall what forcing an object to complain about its type or do not allow to convert data at passing , or allow it / implement it ? You can do pretty much anything with message sending. Super powerful stuff. -- View this message in context: http://forum.world.st/Smalltalk-strongly-typed-tp4701894p4701965.html Sent from the Pharo Smalltalk Developers mailing list archive at Nabble.com.

Aug. 2, 2013

Re: [Pharo-dev] 3.0 rolled back to 30321

by StÃ©phane Ducasse

thanks! Stef On Aug 2, 2013, at 4:14 PM, Esteban Lorenzano <estebanlm(a)gmail.com> wrote: > Hi, > > I needed to rollback to previous integration because there are some problems related to last integration (and Ben is in vacations and cannot deliver a "hot-fix" :) > > Esteban

Aug. 2, 2013

Re: [Pharo-dev] Smalltalk = strongly typed

by Camille Teruel

On 2 aoÃ»t 2013, at 15:47, Esteban Lorenzano wrote: > > On Aug 2, 2013, at 3:39 PM, Camille Teruel <camille.teruel(a)gmail.com> wrote: > >> Just a citation: >> >> âI spent a few weeks ... trying to sort out the terminology of âstrongly typedâ, >> âstatically typedâ, âsafeâ, etc., and found it amazingly difï¬cult ... The usage of these >> terms is so various as to render them almost useless.â >> -- Benjamin C. Pierce >> >> If you use one of these terms, you should give a definition. >> And if you hear one, you shouldn't assume the author means what you think. >> For example some people could argue that Smalltalk is untyped (or unityped [1]), while you argued that it is strongly typed since there is no implicit type conversion. >> For most people, the static/dynamic and the weak/strong distinctions are supposed to be orthogonal. >> So, for most people, strong typing is not a synonymous of static typing. > > I have to say that IMHO, you are wrong in this one. For researchers, maybe. But I have seen in "industry word" that the terms are often exchangeable and for most people I have known, strong=static :( It depends on the people one knows then ;) All that shows that these terms are unclear for everyone and must be defined when used. > >> >> [1] http://existentialtype.wordpress.com/2011/03/19/dynamic-languages-are-stati… >> >> >> On 2 aoÃ»t 2013, at 06:03, btc(a)openInWorld.com wrote: >> >>> greetings all, >>> >>> I'm in the final weeks of writing up my Masters dissertation and seeking some scholarly references to Smalltalk being "Strongly Typed." >>> >>> I my review of Smalltalk I was surprised to find that [1] describes Smalltalk as Strongly Typed, since Smalltalk is sometimes denigrated as being untyped / weakly typed. From reviewing discussion forums this now makes sense, but I can only find one of scholarly reference that briefly mentions this [2]. The most enlightening is [3] which defines Type Strength as: >>> >>> "A strongly typed language prevents any operation on the wrong type of data. In weakly typed languages there are ways to escape this restriction: type conversions" >>> >>> meaning that getting a MNU is a form of Strong Typing since you can't make a Smalltalk object run a method that is not its own. The problem appears to be that Strong Typing has been synonymous with Static Typing for a long time, and Static Typing strongly ties types to variables, except in Dynamically Typed languages, I think types can be considered independently from variables, in which case the definition of [3] has some merit, hence Smalltalk is Strongly Typed. >>> >>> Sounds controversial, so I'm just hoping for some peer reviewed backup - but only you have something easily to hand. This is just a small thing I can just leave out if necessary. >>> >>> cheers -ben >>> >>> [1] http://www.squeak.org/Features/ >>> [2] p15, http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.35.7507&rep=rep1&t… >>> [3] http://www.cs.kuleuven.ac.be/publicaties/rapporten/cw/CW415.pdf >>> >> >

Aug. 2, 2013

3.0 rolled back to 30321

by Esteban Lorenzano

Hi, I needed to rollback to previous integration because there are some problems related to last integration (and Ben is in vacations and cannot deliver a "hot-fix" :) Esteban

Aug. 2, 2013

Re: [Pharo-dev] Smalltalk = strongly typed

by Esteban Lorenzano

On Aug 2, 2013, at 3:39 PM, Camille Teruel <camille.teruel(a)gmail.com> wrote: > Just a citation: > > âI spent a few weeks ... trying to sort out the terminology of âstrongly typedâ, > âstatically typedâ, âsafeâ, etc., and found it amazingly difï¬cult ... The usage of these > terms is so various as to render them almost useless.â > -- Benjamin C. Pierce > > If you use one of these terms, you should give a definition. > And if you hear one, you shouldn't assume the author means what you think. > For example some people could argue that Smalltalk is untyped (or unityped [1]), while you argued that it is strongly typed since there is no implicit type conversion. > For most people, the static/dynamic and the weak/strong distinctions are supposed to be orthogonal. > So, for most people, strong typing is not a synonymous of static typing. I have to say that IMHO, you are wrong in this one. For researchers, maybe. But I have seen in "industry word" that the terms are often exchangeable and for most people I have known, strong=static :( > > [1] http://existentialtype.wordpress.com/2011/03/19/dynamic-languages-are-stati… > > > On 2 aoÃ»t 2013, at 06:03, btc(a)openInWorld.com wrote: > >> greetings all, >> >> I'm in the final weeks of writing up my Masters dissertation and seeking some scholarly references to Smalltalk being "Strongly Typed." >> >> I my review of Smalltalk I was surprised to find that [1] describes Smalltalk as Strongly Typed, since Smalltalk is sometimes denigrated as being untyped / weakly typed. From reviewing discussion forums this now makes sense, but I can only find one of scholarly reference that briefly mentions this [2]. The most enlightening is [3] which defines Type Strength as: >> >> "A strongly typed language prevents any operation on the wrong type of data. In weakly typed languages there are ways to escape this restriction: type conversions" >> >> meaning that getting a MNU is a form of Strong Typing since you can't make a Smalltalk object run a method that is not its own. The problem appears to be that Strong Typing has been synonymous with Static Typing for a long time, and Static Typing strongly ties types to variables, except in Dynamically Typed languages, I think types can be considered independently from variables, in which case the definition of [3] has some merit, hence Smalltalk is Strongly Typed. >> >> Sounds controversial, so I'm just hoping for some peer reviewed backup - but only you have something easily to hand. This is just a small thing I can just leave out if necessary. >> >> cheers -ben >> >> [1] http://www.squeak.org/Features/ >> [2] p15, http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.35.7507&rep=rep1&t… >> [3] http://www.cs.kuleuven.ac.be/publicaties/rapporten/cw/CW415.pdf >> >

Aug. 2, 2013