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This week (16/2023) on the Pharo Issue Tracker

by Marcus Denker

We merged ~60 PRs this week. # Pharo 11 - Backport #13426: Make protocol of super method a priority in MethodClassifier #13432 https://github.com/pharo-project/pharo/pull/13432 - Use fixed spec version for Pharo 11 #13445 https://github.com/pharo-project/pharo/pull/13445 ## GIT/Iceberg (for Pharo 12, too) - 1279 merge menu should indicate the sense of the action #1680 https://github.com/pharo-vcs/iceberg/pull/1680 - Remove unused variable #1695 https://github.com/pharo-vcs/iceberg/pull/1695 - Fix for adding a SSH credential from UI raises an Error #1638 https://github.com/pharo-vcs/iceberg/pull/1638 - Use ED25519 keys as default instead of RSA to improve security and follow new GitHub standards #1649 https://github.com/pharo-vcs/iceberg/pull/1649 - [fix] prevent Iceberg window to crash when the registry is empty #1670 https://github.com/pharo-vcs/iceberg/pull/1670 - Fix for issue #11969 in pharo repository: Better description "packages unloaded packages #1672 https://github.com/pharo-vcs/iceberg/pull/1672 #Pharo 12 ## Enhancements - Completion menu: some love on the detail window #13473 https://github.com/pharo-project/pharo/pull/13473 - Use Pharo12 branch of Spec and NewTools #13460 https://github.com/pharo-project/pharo/pull/13460 - Fix random failure of Ombu in windows. #13448 https://github.com/pharo-project/pharo/pull/13448 - Make protocol of super method a priority in MethodClassifier #13426 https://github.com/pharo-project/pharo/pull/13426 - Cut dependency from CommandLine to UIManager #13431 https://github.com/pharo-project/pharo/pull/13431 - Fix typo introduced in merge #13446 https://github.com/pharo-project/pharo/pull/13446 - Added inspector extensions for RPackage #509 https://github.com/pharo-spec/NewTools/pull/509 ## RPackage and SystemOrganizer - Synch bug in RPackage removal #13496 https://github.com/pharo-project/pharo/pull/13496 ## Protocol and Categories - Keep pushing protocols usage #13443 https://github.com/pharo-project/pharo/pull/13443 - Add some tests on classifications of methods #13485 https://github.com/pharo-project/pharo/pull/13485 - Rename #removeMethodTag: into #removeProtocolIfEmpty: #13492 https://github.com/pharo-project/pharo/pull/13492 - Make #renameProtocolNamed:toBe: manage nils #13480 https://github.com/pharo-project/pharo/pull/13480 - Cleaning of #classify:inProtocolNamed: #13454 https://github.com/pharo-project/pharo/pull/13454 - Deprecate comment management of ClassOrganization #13464 https://github.com/pharo-project/pharo/pull/13464 - Remove ClassOrganization>>#silentlyRenameProtocolNamed:toBe: in favor of always announcing the rename #13458 https://github.com/pharo-project/pharo/pull/13458 - Improve ClassOrganization copy #13453 https://github.com/pharo-project/pharo/pull/13453 - Do not use #classComment #1376 https://github.com/pharo-spec/Spec/pull/1376 ## Compiler: Syntax Hightlight - SHRBTextStyler class>>#blueStyleTable distinguish some variables #13501 https://github.com/pharo-project/pharo/pull/13501 - Improve style for parenthesis, comments and syntax error #13491 https://github.com/pharo-project/pharo/pull/13491 - CodeSnippet: industrialize the testing of the styler #13490 https://github.com/pharo-project/pharo/pull/13490 - add SHRBStyleAttributionTest>>#testErrorStyle #13489 https://github.com/pharo-project/pharo/pull/13489 - Faulty code: improve highlight and icons #13486 https://github.com/pharo-project/pharo/pull/13486 - Fix bug in parenthesis highlight #13467 https://github.com/pharo-project/pharo/pull/13467 ## Compiler: AST - AST: starting visiting comments #13421 https://github.com/pharo-project/pharo/pull/13421 - Snippet: test more comments and fix some #13500 https://github.com/pharo-project/pharo/pull/13500 - Add support to deprecate globals #13348 https://github.com/pharo-project/pharo/pull/13348 - Compiler: expose the AST #13487 https://github.com/pharo-project/pharo/pull/13487 ## Compiler - Snippets: rename (and negate) isMethod to isScripting #13499 https://github.com/pharo-project/pharo/pull/13499 - Vocabulary: propose "script" in compiler #13301 https://github.com/pharo-project/pharo/pull/13301 - OpalCompiler: permit clients to use receiver: after context: as (a noop) #13498 https://github.com/pharo-project/pharo/pull/13498 - Introduce annotations #13449 https://github.com/pharo-project/pharo/pull/13449 - Use Compiler not #copyWithTrailerBytes #13488 https://github.com/pharo-project/pharo/pull/13488 - Directly update source pointer without creating an additional compiled method #13484 https://github.com/pharo-project/pharo/pull/13484 - remove-embeddSourceInTrailer #13481 https://github.com/pharo-project/pharo/pull/13481 - Compiler: remove #optionEmbeddSources #13479 https://github.com/pharo-project/pharo/pull/13479 - Compiler: explicit the need of requestor scope #13472 https://github.com/pharo-project/pharo/pull/13472 - Kill VariableNotDeclared #13471 https://github.com/pharo-project/pharo/pull/13471 - Factorize UndeclaredVariableErrors #13470 https://github.com/pharo-project/pharo/pull/13470 - Debug can recompile doit and uninstalled method #13469 https://github.com/pharo-project/pharo/pull/13469 - Cleanup OpalCompiler & CompilationContext #13423 https://github.com/pharo-project/pharo/pull/13423 - Compiler: simplify DoIt #13398 https://github.com/pharo-project/pharo/pull/13398 - faulty code: test runtimeSyntaxError #13422 https://github.com/pharo-project/pharo/pull/13422 - Rubric editors (thus calypso) execute doit actions in faulty mode #13450 https://github.com/pharo-project/pharo/pull/13450 - Debugger: can handle new exceptions UndeclaredVariableRead&UndeclaredVariableWrite #508 https://github.com/pharo-spec/NewTools/pull/508 - StTestDebuggerProvider class>>#compileMissingClassContextBuilder use permitUndeclared: #506 https://github.com/pharo-spec/NewTools/pull/506 - add missing SpCodeScriptingInteractionModel>>#needRequestorScope #1378 https://github.com/pharo-spec/Spec/pull/1378 - Spec2-Code: declare 'playground'-related capabilities as a compiler requestor #1377 https://github.com/pharo-spec/Spec/pull/1377 ## Cleanups - Refactoring BlockClosureTest >> testCannotReturn #13459 https://github.com/pharo-project/pharo/pull/13459 ## Trivial - use {} instead of Array with:with: #13483 https://github.com/pharo-project/pharo/pull/13483 - use nested and expression #13475 https://github.com/pharo-project/pharo/pull/13475 - use and expression instead of ifTrueifFalse #13477 https://github.com/pharo-project/pharo/pull/13477 - use and expression instead of ifTrueifFalse #13463 https://github.com/pharo-project/pharo/pull/13463 - Use {} instead of "Array with:" for some usages #13461 https://github.com/pharo-project/pharo/pull/13461

April 21, 2023

Re: Picking neighbouring elements

by Richard O'Keefe

successor of x in c = the smallest element of c that is larger than x min {y | y in c . y > x} predecessor of x in c = the largest element of c that is smaller than x max {y | y in c . y < x} On Thu, 20 Apr 2023 at 21:08, Steffen MÃ¤rcker <merkste(a)web.de> wrote: > Dear Richard, > > thanks for that additional piece. I'll put insert-<left/right> on my list > of possible variants. I think we come back to naming after the initial port > is done and everyone can play with it. Generally, I made the observation to > better be careful with names since it's too easy to alienate other or > trigger wrong assumptions. > > New topic! (quote below) > > Honestly, my knowledge of Haskell is rather limited and rusted. Hence, I > am having difficulties understanding what exactly these operations with a > sequence of elements. Can you give an example or some pseude/smalltalk code > from your use-case and library? > > Kind regards > > > Changing the subject a wee bit, there's an operation family > in my library, and I wonder how it would fit into Transducers? > To avoid bias, here's a specification in Haskell (for lists, > because I haven't had any luck installing Data.Witherable). > > uccessorBy, predecessorBy :: (a -> a -> Ordering) -> a -> [a] -> a > successor, predecessor :: Ord a => a -> [a] -> a > > successor = successorBy compare > > successorBy cmp x = minimumBy cmp . filter (\y -> cmp x y == LT) > > predecessor = predecessorBy compare > > predecessorBy cmp = successorBy (flip cmp) > > The reason these operations exist is to pick neighbouring > elements in SortedCollections and SortedSets. But they make > *sense* for any Enumerable. So there are "generic" > definitions with orderrides for those two classes. > > A filter + a reduce . Traditionally, a #select:thenFold:ifNone: > in order to avoid building an intermediate collection. That much > I see how to do with transducers. But you can't get the desired > override for #successor:[sortBlock:][ifNone:] by overriding > #select:thenFold:ifNone: in SortedCollection or SortedSet. So what > *should* one do? > >

April 21, 2023

Yoshiki Ohshima - Croquet Microverse - 26 April 2023

by Giovanni Corriga

For this month's online presentation, Yoshiki Ohshima will demonstrate the Croquet Microverse ( https://croquet.io/ ), which is a 3D collaborative construction environment. It is an incarnation of Smalltalk-based Croquet but instead implemented in JavaScript. Microverse allows a group of users to collaboratively create new objects in a virtual space, and describe their behaviors in the live programming manner that can be used by professional programmers. The object extension mechanism used in the Microverse is heavily influenced by past class and object extension mechanisms, many of which originated from experimentation and implementation in Smalltalk. Likewise, the architecture of the Microverse application framework draws upon other frameworks such as Morphic and AppKit. Yoshiki will explain the connections between those systems and the Microverse. Yoshiki ( https://tinlizzie.org/ohshima/ ) joined Walt Disney Imagineering R&D in 2000 as an intern while attending the graduate school of Tokyo Institute of Technology, and helped develop prototypes of Disney's theme park attractions. He also has been involved in Alan Kay's research group, and participated in the research and development effort of education programming environment Squeak Etoys and later took the leading role. Yoshiki has worked at the Viewpoints Research Institute, SAP Labs CDG, and Y Combinator Research, all of which Dr. Kay founded or helped found. He was awarded his PhD. for designing and implementing a massively parallel particle programming system from Tokyo Institute of Technology. This will be an online meeting from home. If you'd like to join us, please sign up in advance on the meeting's Meetup page ( https://www.meetup.com/ukstug/events/292570084/ ) to receive the meeting details.

April 20, 2023

Re: Picking neighbouring elements

by Steffen MÃ¤rcker

Dear Richard, thanks for that additional piece. I'll put insert-<left/right> on my list of possible variants. I think we come back to naming after the initial port is done and everyone can play with it. Generally, I made the observation to better be careful with names since it's too easy to alienate other or trigger wrong assumptions. New topic! (quote below) Honestly, my knowledge of Haskell is rather limited and rusted. Hence, I am having difficulties understanding what exactly these operations with a sequence of elements. Can you give an example or some pseude/smalltalk code from your use-case and library? Kind regards Changing the subject a wee bit, there's an operation family in my library, and I wonder how it would fit into Transducers? To avoid bias, here's a specification in Haskell (for lists, because I haven't had any luck installing Data.Witherable). uccessorBy, predecessorBy :: (a -> a -> Ordering) -> a -> [a] -> a successor, predecessor :: Ord a => a -> [a] -> a successor = successorBy compare successorBy cmp x = minimumBy cmp . filter (\y -> cmp x y == LT) predecessor = predecessorBy compare predecessorBy cmp = successorBy (flip cmp) The reason these operations exist is to pick neighbouring elements in SortedCollections and SortedSets. But they make *sense* for any Enumerable. So there are "generic" definitions with orderrides for those two classes. A filter + a reduce . Traditionally, a #select:thenFold:ifNone: in order to avoid building an intermediate collection. That much I see how to do with transducers. But you can't get the desired override for #successor:[sortBlock:][ifNone:] by overriding #select:thenFold:ifNone: in SortedCollection or SortedSet. So what *should* one do?

April 20, 2023

Re: Collection>>reduce name clash with transducers

by Richard O'Keefe

I've always called the block in #inject:into: the *combining* function. Perhaps the reason I don't think of it as a "reducing" function is that setOfSets inject: Set new into: [:acc :each | acc union: each] has a block that combines its arguments in a way that makes the result bigger, not smaller. For what it's worth, Backus used "insert": *insert-right* /*f* where /*f*:ã*x*ã = *x* and /*f*:ã*x*1,*x*2,...,*x*nã = *f*:ã*x*1,/*f*:ã*x*2,...,*x*nãã and /*f*:ã ã = *unit f* *insert-left* \*f* where \*f*:ã*x*ã = *x* and \*f*:ã*x*1,*x*2,...,*x*nã = *f*:ã\*f*:ã*x*1,...,*x*n-1ã,*x*nã and \*f*:ã ã = *unit f* --- https://en.wikipedia.org/wiki/FP_(programming_language) Every day spent debating the words is another day the software isn't getting used, so I'm sorry about prolonging this. Some names are just too confusing. Some years ago, I found it useful to add {value:}...{optionalValue:}... to my library for passing arguments that the receiver may choose to ignore. (The methods are exactly as direct as the {value:}... methods, no extra allocations or anything.) About the same time, Pharo independenty added {cull:}... but it was years before I noticec, because "cull" to me means either (a) to slaughter a large proportion of a population of wild or domestic anmals, or (b) to gather information from a large number of sources. (The concept "reap" is lurking somewhere in the background.) I don't know who came up with that name for pass-optional-argument, but it grates so much I can't bring myself to use it and just make do without optional parameters in Pharo. In fact it was this example that was at the back of my mind. Changing the subject a wee bit, there's an operation family in my library, and I wonder how it would fit into Transducers? To avoid bias, here's a specification in Haskell (for lists, because I haven't had any luck installing Data.Witherable). uccessorBy, predecessorBy :: (a -> a -> Ordering) -> a -> [a] -> a successor, predecessor :: Ord a => a -> [a] -> a successor = successorBy compare successorBy cmp x = minimumBy cmp . filter (\y -> cmp x y == LT) predecessor = predecessorBy compare predecessorBy cmp = successorBy (flip cmp) The reason these operations exist is to pick neighbouring elements in SortedCollections and SortedSets. But they make *sense* for any Enumerable. So there are "generic" definitions with orderrides for those two classes. A filter + a reduce . Traditionally, a #select:thenFold:ifNone: in order to avoid building an intermediate collection. That much I see how to do with transducers. But you can't get the desired override for #successor:[sortBlock:][ifNone:] by overriding #select:thenFold:ifNone: in SortedCollection or SortedSet. So what *should* one do?

April 20, 2023

Re: Project and package structure recommendations

by Steffen MÃ¤rcker

Thank you both for your answers. That is certainly helpful. - I just noticed that most (all?) package names in the Pharo image do not contain spaces although it is possible to create such names. Is this discouraged or are there issues to watch out for? - Is there a reference how the name mangling of packages, categories and such works? For instance, it seems if a class def states "MyPackage-Tests" it appears in MyPackage under the category tests. Kind regards, Steffen Noury Bouraqadi schrieb am Mittwoch, 19. April 2023 19:10:13 (+02:00): BTW, Beside this mailing list, there is the Pharo Discord for discussions. Noury On Apr 19 2023, at 7:06 pm, Gabriel Cotelli <g.cotelli(a)gmail.com> wrote: Most projects that I'm aware of, follow something like this: - 1 project per git repository - One or more packages for the functional part, separate packages for the tests (because if you only use categories you can't load only the runtime required code and exclude the tests) - If your project has optional parts, and this code is in different packages you can provide in the Baseline "groups" for loading sub-sets of the packages Usually, we use https://github.com/ba-st/GitHub-setup for generating the initial boilerplate of new projects. Regards, Gabriel On Wed, Apr 19, 2023 at 12:55â¯PM Steffen MÃ¤rcker <merkste(a)web.de> wrote: Hi, I'd like to ask for your advice or best practices regarding the package structure of a project. So far I have understood: - Iceberg can store multiple packages (project?) in a git repository - A package (or multiple?) and its dependencies is loaded via a baseline - A package can have flags (= categories?) Suppose, a project has - A core part - One or multipel optional parts, that a user may or may not want to load, too - Tests for the core - Tests for each optional part What's the recommended way to structure this in Pharo? For example, I've seen that some code in Pharo has its tests in the same package but flagged/categorized, other code has a separate package for tests. Also, can a (git) repository have multiple baselines? Sorry, if I am asking the obvious but I did not manage to find guidlines in the documentation yet. It might very well an oversight be myself. Kind regards, Steffen -- Gesendet mit Vivaldi Mail. Laden Sie Vivaldi kostenlos unter vivaldi.com herunter

April 20, 2023

Re: Project and package structure recommendations

by Noury Bouraqadi

BTW, Beside this mailing list, there is the Pharo Discord for discussions. Noury On Apr 19 2023, at 7:06 pm, Gabriel Cotelli <g.cotelli(a)gmail.com> wrote: > Most projects that I'm aware of, follow something like this: > > - 1 project per git repository > > - One or more packages for the functional part, separate packages for the tests (because if you only use categories you can't load only the runtime required code and exclude the tests) > - If your project has optional parts, and this code is in different packages you can provide in the Baseline "groups" for loading sub-sets of the packages > > Usually, we use https://github.com/ba-st/GitHub-setup for generating the initial boilerplate of new projects. > > Regards, > Gabriel > > > > On Wed, Apr 19, 2023 at 12:55â¯PM Steffen MÃ¤rcker <merkste(a)web.de (mailto:merkste@web.de)> wrote: > > Hi, > > > > I'd like to ask for your advice or best practices regarding the package > > structure of a project. So far I have understood: > > - Iceberg can store multiple packages (project?) in a git repository > > - A package (or multiple?) and its dependencies is loaded via a baseline > > - A package can have flags (= categories?) > > > > Suppose, a project has > > - A core part > > - One or multipel optional parts, that a user may or may not want to load, > > too > > - Tests for the core > > - Tests for each optional part > > > > What's the recommended way to structure this in Pharo? For example, I've > > seen that some code in Pharo has its tests in the same package but > > flagged/categorized, other code has a separate package for tests. Also, can > > a (git) repository have multiple baselines? > > > > Sorry, if I am asking the obvious but I did not manage to find guidlines in > > the documentation yet. It might very well an oversight be myself. > > > > Kind regards, > > Steffen > >

April 19, 2023

Re: Project and package structure recommendations

by Gabriel Cotelli

Most projects that I'm aware of, follow something like this: - 1 project per git repository - One or more packages for the functional part, separate packages for the tests (because if you only use categories you can't load only the runtime required code and exclude the tests) - If your project has optional parts, and this code is in different packages you can provide in the Baseline "groups" for loading sub-sets of the packages Usually, we use https://github.com/ba-st/GitHub-setup for generating the initial boilerplate of new projects. Regards, Gabriel On Wed, Apr 19, 2023 at 12:55â¯PM Steffen MÃ¤rcker <merkste(a)web.de> wrote: > Hi, > > I'd like to ask for your advice or best practices regarding the package > structure of a project. So far I have understood: > - Iceberg can store multiple packages (project?) in a git repository > - A package (or multiple?) and its dependencies is loaded via a baseline > - A package can have flags (= categories?) > > Suppose, a project has > - A core part > - One or multipel optional parts, that a user may or may not want to load, > too > - Tests for the core > - Tests for each optional part > > What's the recommended way to structure this in Pharo? For example, I've > seen that some code in Pharo has its tests in the same package but > flagged/categorized, other code has a separate package for tests. Also, can > a (git) repository have multiple baselines? > > Sorry, if I am asking the obvious but I did not manage to find guidlines in > the documentation yet. It might very well an oversight be myself. > > Kind regards, > Steffen >

April 19, 2023

Project and package structure recommendations

by Steffen MÃ¤rcker

Hi, I'd like to ask for your advice or best practices regarding the package structure of a project. So far I have understood: - Iceberg can store multiple packages (project?) in a git repository - A package (or multiple?) and its dependencies is loaded via a baseline - A package can have flags (= categories?) Suppose, a project has - A core part - One or multipel optional parts, that a user may or may not want to load, too - Tests for the core - Tests for each optional part What's the recommended way to structure this in Pharo? For example, I've seen that some code in Pharo has its tests in the same package but flagged/categorized, other code has a separate package for tests. Also, can a (git) repository have multiple baselines? Sorry, if I am asking the obvious but I did not manage to find guidlines in the documentation yet. It might very well an oversight be myself. Kind regards, Steffen

April 19, 2023

Re: Collection>>reduce name clash with transducers

by Steffen MÃ¤rcker

Dear Richard, sorry for the delayed reply and thanks for your thoughts. I wrapped my head around your suggestions and tried a few thing to see how the play out in code. I tend towards the following names. - Reducing function (a role) is a binary block / object that responds to #value:value: and #numArgs; commonly used with #inject:into: - Completing function (a role) is an unary block / object that responds to #value:. - Reducer is a pair (rfn, cfn) of a reducing function and a completing function. - Reduction is a pair (red, val) of a reducer and an initial value. I like your idea to inverse the message flow and implement #reduce: in Reduction. It reads well in my eyes in actual code. I do not think that this is a misnomer, since it indeed reduces a sequence of elements to a single object. A reducer knows how to apply first its rfn to a sequence and then cfn to the result. negatedSum := (#+ completing: #negate) init: 0. result := negatedSum reduce: (1 to: 10). asSet := (#add completing: #trim) initializer: [Set new]. distinct := asSet reduce: aCollection I understand your concerns that we usually either do not need cfn or we applies it manually to the result of the reduction. Yes, most often cfn = identity and I took this into account. However, in some cases I actually need them to pass around as a single object. I also attempted to find names closer to #inject:into: but did not come up with any good ideas yet. That this makes sense so far? I deliberately did not mention transducers above to focus on the naming first. I heard about "obviously synchronizable series expressions" before and had a look at the paper just now. In short, transducers are in the same spirit and offer similar nice properties. But maybe we save the details for another thread? Regarding the examples. Yes, they are are simple, stupid and the reimplemenation of #reduce: is far from optimal. The goal was to show how the objects/messages are used rather then coming up with real world examples or showing off. ;-) Kind regards, Steffen Richard O'Keefe schrieb am Samstag, 15. April 2023 16:28:09 (+02:00): Let initial :: a combine :: a -> b -> a finish :: a -> c then (finish . foldl combine initial) :: Foldable t => t b -> c This appears to be analogous to your 'reduce with completion'. What *can* be done with composition generally *should* be done with composition; I really don't see any advantage in defining reduce finish combine initial = finish . combine initial As for growing a collection and then finally trimming it to its desired size, I've never known anything like that to be a good idea. There's a reason why my library includes Set BoundedSet IdentitySet BoundedIdentitySet Deque BoundedDeque Heap BoundedHeap I use BoundedHeap a lot. If I want to find the k best things out of n, using BoundedHeap lets me do it in O(n.log k) time and O(k) space instead of O(n.log n) time and O(n) space. Your example showing how much better #reduceLeft: is when expressed using transducers is not well chosen,because the implementation of #reduceLeft: in Pharo is (how to say this politely?) not up to the standards we expect from Pharo. Here is how it stands in my compatibility library: Enumerable methods for: 'summarising' reduceLeft: aBlock <compatibility: #pharo> |n| ^(n := aBlock argumentCount) > 2 ifTrue: [ |i a| a := Array new: n. i := 0. self do: [:each | a at: (i := i + 1) put: each. i = n ifTrue: [ a at: (i := 1) put: (aBlock valueWithArguments: a)]]. i = 1 ifTrue: [a at: i] ifFalse: [ self error: 'collection/block size mismatch']] ifFalse: [ "If n = 0 or 1 and the receiver has two or more elements, this will raise an exception passing two arguments to aBlock. That's a good way to complain about it." |r f| r := f := nil. self do: [:each | r := f ifNil: [f := self. each] ifNotNil: [aBlock value: r value: each]]. r == f ifNil: [CollectionTooSmall collection: self] ifNotNil: [r]] No OrderedCollection. And exactly one traversal of the collection. (Enumerables can only be traversed once. Collections can be traversed multiple times.) The only method the receiver needs to provide is #do:, so this method doesn't really need to be in Enumerable. It could, for example, be in Block. #reduceRight: I've placed in AbstractSequence because it needs #reverseDo:, but it equally makes sense as a method of Block (as it knows more about what Blocks can do than it does about what sequences can do). For example, I have SortedSet and SortedBag which can be traversed forwards and backwards but only #reduceLeft: is available to them; #reduceRight: is not, despite them sensibly supporting #reverseDo:. For that matter, Deques support #reverseDo: but are not sequences... To the limited extent that I understand the Transducers package, this view that (s reduce{Left,Right}: b) should really be (b reduce{Left,Right}) applyTo: s seems 100% in the spirit of Transducers. In fact, now that I understand a bit about Transducers, <collection> reduce: <transducer> (a) seems back to front compared with <reducer> applyTo: <collection> (b) seems like a misnomer because in general much may be generated transformed and retained, with nothing getting smaller, so why 'reduce'? It seems like a special case of applying a function-like object (the transducer) to an argument (the collection), so why not transducer applyTo: dataSource transducer applyTo: dataSource initially: initial Did you look at Richard Waters' "obviously synchronizable series expressions"? (MIT AI Memo 958A and 959A) Or his later SERIES package? (Appendix A of Common Lisp the Language, 2nd edition) On Fri, 14 Apr 2023 at 22:32, Steffen MÃ¤rcker <merkste(a)web.de> wrote: Hi Richard! Thanks for sharing your thoughts. There's a reason why #inject:into: puts the block argument last. It works better to have "heavy" constituents on the right in an English sentence, and it's easier to indent blocks when they come last. Nice, I never though of it this way. I always appreciate a historical background. Let me try to respond to the rest with a focus on the ideas. First of all, the point of the transducers framework is to cleanly separate between iteration over sequences, processing of the elements and accumulation of a result. It enables easy reuse the concepts common to different data structures. 1. What do I mean by completion? If we iterate over a sequence of objects, we sometimes want to do a final step after all elements have seen to complete the computation. For instance, after copying elements to a new collection, we may want to trim it to its actual size: distinct := col inject: Set new into: #add. distinct trim. For some cases it turns out to be useful to have an object that knows how to do both: distinct := col reduce: (#add completing: #trim) init: Set new. #reduce:init: knows how to deal with both this new objects and ordinary blocks. For now I will call both variants a "reducing function". Note, completion is completely optional and the implementation is literally #inject:into: plus completion if required. 2. What is a reduction? In some cases, it turns out to be useful to pair up a reducing function with an (initial) value. You called it a magma and often its indeed the neutral element of a mathematical operator, e.g., + and 0. But we can use a block that yields the initial value, too. For instance: sum := #+ init: 0. result := numbers reduce: sum. toSet := (#add completing: #trim) initializer: [Set new]. distinct := col reduce: toSet. #reduce: is just a shorthand that passes the function and the value to #reduce:init: Maybe #reduceMagma: is a reasonable name? 3. The reason I implemented #reduce:init: directly on collections, streams, etc. is that these objects know best how to efficiently iterate over their elements. And if a data structure knows how to #reduce:init: we can use it with all the transducers functions, e.g., for partitioning, filtering etc. Other useful methods could then be added to the behaviour with a trait, e.g., #transduce:reduce:init which first apples a transducer and then reduces. As traits are not available in plain VW 8.3, I did not try this approach, though. 4. Lets take #reduce:Left: as and example and reimplement the method using transducers, shall we? The following code works for each sequence/collection/stream that supports #transduce:reduce:init: reduceLeft: aBlock | head rest arity | head := self transduce: (Take number: 1) reduce: [:r :e | e] init: nil. rest := Drop number: 1. arity := aBlock arity. ^arity = 2 ifTrue: [self transduce: rest reduce: aBlock init: head] ifFalse: [ | size arguments | size := arity - 1. rest := rest * (Partition length: size) * (Remove predicate: [:part | part size < size]). arguments := Array new: arity. arguments at: 1 put: head. self transduce: rest reduce: ([:args :part | args replaceFrom: 2 to: arity with: part; at: 1 put: (aBlock valueWithArguments: args); yourself] completing: [:args | args first]) init: arguments] This code is both more general and faster: It does not create an intermediate OrderedCollection and it treats the common case of binary blocks efficiently. Note the implementation can more compact and optimized if it was specialized in certain class. For instance, SequenceableCollection allows accessing elements by index which turns the first line into a simple "self first". Thanks for staying with me for this long reply. I hope I did not miss a point. I do not insist on the existing names but will appreciate any ideas. Best, Steffen Richard O'Keefe schrieb am Freitag, 14. April 2023 09:43:32 (+02:00): #reduce: aReduction Are you saying that aReduction is an object from which a dyadic block and an initial value can be derived? That's going to confuse the heck out of Dolphin and Pharo users (like me, for example). And in my copy of Pharo, #reduce: calls #reduceLeft:, not #foldLeft:. The sad thing about #reduceLeft: in Pharo is that in order to provide extra generality I have no use for, it fails to provide a fast path for the common case of a dyadic block. reduceLeft: aBlock aBlock argumentCount = 2 ifTrue: [ |r| r := self first. self from: 2 to: self last do: [:each | r := aBlock value: r value: each]. ^r]. ... everything else as before ... Adding up a million floats takes half the time using the fast path (67 msec vs 137 msec). Does your #reduce: also perform "a completion action"? If so, it definitely should not be named after #inject:into:. At any rate, if it does something different, it should have a different name, so #reduce: is no good. #reduce:init: There's a reason why #inject:into: puts the block argument last. It works better to have "heavy" constituents on the right in an English sentence, and it's easier to indent blocks when they come last. Which of the arguments here specifies the 'completion action'? What does the 'completion action' do? (I can't tell from the name.) I think the answer is clear: * choose new intention-revealing names that do not clash. If I have have understood your reduce: aReduction correctly, a Reduction specifies - a binary operation (not necessarily associative) - a value which can be passed to that binary operation which suggests that it represents a magma with identity. By the way, it is not clear whether {x} reduce: <<ident. binop>> answers x or binop value: ident value: x. It's only when ident is an identity for binop that you can say 'it doesn't matter'. I don't suppose you could bring yourself to call aReduction aMagmaWithIdentity? Had you considered aMagmaWithIdentity reduce: aCollection where the #reduce: method is now in your class so can't *technically* clash with anything else? All you really need from aCollection is #do: so it could even be a stream. MagmaWithIdentity >> identity >> combine:with: >> reduce: anEnumerable |r| r := self identity. anEumerable do: [:each | r := self combine: r with: each]. ^r MagmaSansIdentity >> combine:with: >> reduce: anEnumerable |r f| f := r := nil. anEnumerable do: [:each | r := f ifNil: [f := self. each] ifNotNil: [self combine: r with: each]]. f ifNil: [anEnumerable error: 'is empty']. ^r On Fri, 14 Apr 2023 at 05:02, Steffen MÃ¤rcker <merkste(a)web.de> wrote: The reason I came up with the naming question in the first place is that I (finally !) finish my port of Transducers to Pharo. But currently, I am running into a name clash. Maybe you have some good ideas how to resolve the following situation in a pleasant way. - #fold: exists in Pharo and is an alias of #reduce: - #reduce: exists in Pharo and calls #foldLeft: which also deals with more than two block arguments Both of which are not present in VW. Hence, I used the following messages in VW with no name clash: - #reduce: aReduction "= block + initial value" - #reduce:init: is similar to #inject:into: but executes an additional completion action Some obvious ways to avoid a clash in Pharo are: 1) Make #reduce: distinguish between a reduction and a simple block (e.g. by double dispatch) 2) Rename the transducers #reduce: to #injectInto: and adapt #inject:into: to optionally do the completion 3) Find another selector that is not too counter-intuitive All three approaches have some downsides in my opinion: 1) Though straight forward to implement, both flavors behave quite different, especially with respect to the number of block arguments. The existing one creates a SequenceableCollection and partitions it according to the required number of args. Transducers' #reduce: considers binary blocks as the binary fold case but ternary blocks as fold with indexed elements. 2) This is a real extension of #inject:into: but requires to touch multiple implementations of that message. Something I consider undesirabe. 3) Currently, I cannot think of a good name that is not too far away from what we're familiar with. Do you have some constructive comments and ideas? Kind regards, Steffen Steffen MÃ¤rcker schrieb am Donnerstag, 13. April 2023 17:11:15 (+02:00): :-D I don't know how compress made onto that site. There is not even an example in the list of language examples where fold/reduce is named compress. Richard O'Keefe schrieb am Donnerstag, 13. April 2023 16:34:29 (+02:00): OUCH. Wikipedia is as reliable as ever, I see. compress and reduce aren't even close to the same thing. Since the rank of the result of compression is the same as the rank of the right operand, and the rank of the result of reducing is one lower, they are really quite different. compress is Fortran's PACK. https://gcc.gnu.org/onlinedocs/gfortran/PACK.html On Fri, 14 Apr 2023 at 01:34, Steffen MÃ¤rcker <merkste(a)web.de> wrote: Hi Richard and Sebastian! Interesting read. I obviously was not aware of the variety of meanings for fold/reduce. Thanks for pointing this out. Also, in some languages it seems the same name is used for both reductions with and without an initial value. There's even a list on WP on the matter: https://en.wikipedia.org/wiki/Fold_%28higher-order_function%29#In_various_l… Kind regards, Steffen Richard O'Keefe schrieb am Donnerstag, 13. April 2023 13:16:28 (+02:00): The standard prelude in Haskell does not define anything called "fold". It defines fold{l,r}{,1} which can be applied to any Foldable data (see Data.Foldable). For technical reasons having to do with Haskell's non-strict evaluation, foldl' and foldr' also exist. But NOT "fold". https://hackage.haskell.org/package/base-4.18.0.0/docs/Data-Foldable.html#l… On Thu, 13 Apr 2023 at 21:17, Sebastian Jordan Montano <sebastian.jordan(a)inria.fr> wrote: Hello Steffen, Let's take Kotlin documentation (https://kotlinlang.org/docs/collection-aggregate.html#fold-and-reduce) > The difference between the two functions is that fold() takes an initial value and uses it as the accumulated value on the first step, whereas the first step of reduce() uses the first and the second elements as operation arguments on the first step. Naming is not so consistent in all the programming languages, they mix up the names "reduce" and "fold". For example in Haskell "fold" does not take an initial value, so it is like a "reduce" in Kotlin. In Kotlin, Java, Scala and other oo languages "reduce" does not take an initial value while "fold" does. Pharo align with those languages (except that out fold is called #inject:into:) So for me the Pharo methods #reduce: and #inject:into represent well what they are doing and they are well named. Cheers, Sebastian ----- Mail original ----- > De: "Steffen MÃ¤rcker" <merkste(a)web.de> > Ã: "Any question about pharo is welcome" <pharo-users(a)lists.pharo.org> > EnvoyÃ©: Mercredi 12 Avril 2023 19:03:01 > Objet: [Pharo-users] Collection>>reduce naming > Hi! > > I wonder whether there was a specific reason to name this method #reduce:? > I would have expected #fold: as this is the more common term for what it > does. And in fact, even the comment reads "Fold the result of the receiver > into aBlock." Whereas #reduce: is the common term for what we call with > #inject:into: . > > I am asking not to annoy anyone but out of curiosity. It figured this out > only by some weird behaviour after porting some code that (re)defines > #reduce . > > Ciao! > Steffen -- Gesendet mit Vivaldi Mail. 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April 17, 2023