Hi Rick,

Thanks for taking the time to reply. I discussed the same argument with Ankit 
Aggarwal, and here are my counter-arguments:

It seems to me like the survey should take into account the developer 
population using each tool. If we are doing such a survey to see what tool a 
programmer coming to Swift is coming from, there is much less chance he has 
previous knowledge of rebar3 than of npm. The majority of the ones which are 
widely used seem to use install: I’ve updated the survey bellow by ordering 
them by stars on GitHub. It’s a crude approximation of developer population, 
but I think it’s good enough for us.
If we do end up implementing install to mean install to the system, how would 
we update the system packages?
Solution 1 would be to add a —system/—global flag on update. In that case, that 
would bring inconsistency by using two different commands to “install/resolve” 
and one command but different flags for updating.
Solution 2 would be to introduce a different command to update, for example 
upgrade. In that case, we get into the scenario of Homebrew, where two 
synonymous commands (update and upgrade) are used to do two different things (I 
have a hard time remembering which is which).
As can be seen in the table bellow, all package managers which offer both an 
installation for the local project and for the system always use the same 
commands names for both. I would vote for a system where:

install [package]: resolves and fetches one or all packages locally in the 
project
install —system package: fetches and installs a specific package in the system
update [package]: resolves and updates one or all packages locally in the 
project
update —system package: updates a specific package in the system
Here is the same survey you did, but with more information:

Package Manager GitHub Stars    Language        Resolved File Name      Local 
Install Command   Local Update Command    System Install Command  System Update 
Command
Yarn    24711   JS      yarn.lock       install upgrade global install  global 
upgrade
NPM     12214   JS      npm-shrinkwrap.json     install update  install -g      
update -g
CocoaPods       9328    ObjC/Swift      Podfile.lock    install update  N/A     
N/A
Carthage        9320    ObjC/Swift      Cartfile.resolved       bootstrap       
update  N/A     N/A
Composer        9313    PHP     composer.lock   install update  N/A     N/A
Glide   4349    Go      glide.lock      install update  N/A     N/A
Bundler 3771    Ruby    Gemfile.lock    install update  install(with gem)       
update(with gem)
Pip     3555    Python  requirements.txt        N/A     N/A     install install 
--upgrade
Cargo   2206    Rust    Cargo.lock      N/A     update  N/A     N/A
rebar3  622     Erlang  rebar.lock      get-deps        upgrade N/A     N/A
Carton  393     Perl    carton.lock     install update  N/A     N/A
Pub     40      Dart    pubspec.lock    get     upgrade N/A     N/A
Meteor  N/A (1) JS      versions        add     update  N/A     N/A
Mix     N/A (2) Elixir  mix.lock        deps.get        deps.update     N/A     
N/A
We only have the number of GitHub stars for the the whole Meteor project 
(37255) - so are not easily comparable with the stars for other package manager 
projects in the list.
We only have the number of GitHub stars for the the whole Elixir project (9928) 
- so are not easily comparable with the stars for other package manager 
projects in the list.

> On 30 Apr 2017, at 06:06, Rick Ballard <rball...@apple.com> wrote:
> 
> Thanks for the feedback, David, and apologies for the slow reply. My biggest 
> reservation with the word "install" is that it really sounds like it should 
> install things into the system, or another shareable location, instead of 
> fetching dependencies into the dependency location for a single top-level 
> package. We might actually want to add a real "install" command that does 
> some type of installation some day in the future, though we might also choose 
> to forever leave that sort of thing to your system package manager. And while 
> there is some precedence for other package managers using "install" to fetch 
> dependencies, I think there's broader precedence for it meaning to either 
> install things into the system, or at least create an installable "build 
> root", with e.g. `make install`, `xcodebuild install`, `brew install`, etc.
> 
> I just did a quick survey of the same package managers I surveyed previously 
> to see if they all used this term, and here's what I found:
> 
> yarn: `install`
> composer: `install`
> cargo: No true equivalent, just supprts `update` or `build`. Also, uses 
> `install` to mean something different – `cargo install` installs binary 
> packages only, to a installation root.
> bundler: `install`
> cocoapods: `install`
> glide: `install`
> pub: `get`
> mix: `deps.get`
> rebar3: `get-deps`
> carton: `install`
> carthage: `bootstrap`
> pip: Uses `install`, but since pip doesn't enforce the top-level-package 
> seperation of SwiftPM, Pip's use of `install` is actually more accurate.
> npm: `install`
> meteor: no true equivalent, just supports `update` or `build`
> 
> Given that this isn't a universal term, I think I'm comfortable going against 
> the flow a little bit if it means that we get to have clear and accurate 
> command-line verbs. But I think this is worth adding to the "Alternatives 
> Considered" section before we put this up for review!
> 
>       - Rick
> 
>> On Apr 26, 2017, at 10:42 PM, David Hart <da...@hartbit.com 
>> <mailto:da...@hartbit.com>> wrote:
>> 
>> Very happy about this proposal as the pinning feature was un-necessarily 
>> complicated and because SwiftPM will now work like many other package 
>> managers out there: users won't be surprised.
>> 
>> By the way, why wasn't resolve called install instead, mirroring the 
>> terminology used everywhere else? It feels like the name was chosen 
>> specifically to denote that it's doing something different than other 
>> dependency managers out there. But that doesn't seem to be the case.
>> 
>> On 27 Apr 2017, at 02:25, Rick Ballard via swift-evolution 
>> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
>> 
>>> Hi all,
>>> 
>>> We have a proposal we'd like feedback on to revise how Swift Package 
>>> Manager dependency resolution, updating, and pinning works. These changes 
>>> weren't planned in the roadmap we published a few months ago, but it's 
>>> become clear since then that we have some holes in our dependency 
>>> resolution behavior that need fixing. We've also come to the conclusion 
>>> that our original design for pinning was overcomplicated and should be 
>>> revised.
>>> 
>>> Please give us your feedback; we're hoping to submit this proposal for 
>>> official review next week.
>>> 
>>> The current draft of the proposal can be found at 
>>> https://github.com/rballard/swift-evolution/commit/e5e7ce76f29c855aa7162ed3733b09e701d662d6
>>>  
>>> <https://github.com/rballard/swift-evolution/commit/e5e7ce76f29c855aa7162ed3733b09e701d662d6>.
>>>  I'm also including it below.
>>> 
>>> Thanks,
>>> 
>>>     - Rick
>>> 
>>> Package Manager Revised Dependency Resolution
>>> 
>>> Proposal: SE-NNNN 
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md>
>>> Author: Rick Ballard <https://github.com/rballard>
>>> Review Manager: TBD
>>> Status: Draft in progress
>>> Bug: TBD
>>>  
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md#introduction>Introduction
>>> 
>>> This proposal makes the package manager's dependency resolution behavior 
>>> clearer and more intuitive. It removes the pinning commands (swift package 
>>> pin & swift package unpin), replaces the swift package fetch command with a 
>>> new swift package resolve command with improved behavior, and replaces the 
>>> optional Package.pins file with a Package.resolved file which is always 
>>> created during dependency resolution.
>>> 
>>>  
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md#motivation>Motivation
>>> 
>>> When SE-0145 Package Manager Version Pinning 
>>> <https://github.com/apple/swift-evolution/blob/master/proposals/0145-package-manager-version-pinning.md>
>>>  was proposed, it was observed that the proposal was overly complex. In 
>>> particular, it introduced a configuration option allowing some packages to 
>>> have autopinning on (the default), while others turned it off; this option 
>>> affected the behavior of other commands (like swift package update, which 
>>> has a --repinflag that does nothing for packages that use autopinning). 
>>> This configuration option has proved to be unnecessarily confusing.
>>> 
>>> In the existing design, when autopinning is on (which is true by default) 
>>> the swift package pin command can't be used to pin packages at specific 
>>> revisions while allowing other packages to be updated. In particular, if 
>>> you edit your package's version requirements in the Package.swift manifest, 
>>> there is no way to resolve your package graph to conform to those new 
>>> requirements without automatically repinning all packages to the latest 
>>> allowable versions. Thus, specific, intentional pins can not be preserved 
>>> without turning off autopinning.
>>> 
>>> The problems here stem from trying to use one mechanism (pinning) to solve 
>>> two different use cases: wanting to record and share resolved dependency 
>>> versions, vs wanting to keep a badly-behaved package at a specific version. 
>>> We think the package manager could be simplified by splitting these two use 
>>> cases out into different mechanisms ("resolved versions" vs "pinning"), 
>>> instead of using an "autopinning" option which makes these two features 
>>> mutually-exclusive and confusing.
>>> 
>>> Additionally, some dependency resolution behaviors were not well-specified 
>>> and do not behave well. The package manager is lax about detecting changes 
>>> to the versions specified in the Package.swift manifest or 
>>> Package.pinspinfile, and fails to automatically update packages when 
>>> needed, or to issue errors if the version requirements are unsatisfiable, 
>>> until the user explicitly runs swift package update, or until a new user 
>>> without an existing checkout attempts to build. We'd like to clarify and 
>>> revise the rules around when and how the package manager performs 
>>> dependency resolution.
>>> 
>>>  
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md#proposed-solution>Proposed
>>>  solution
>>> 
>>> The pinning feature will be removed. This removes the swift package pin and 
>>> swift package unpin commands, the --repin flag to swift package update, and 
>>> use of the Package.pins file.
>>> 
>>> In a future version of the package manager we may re-introduce pinning. If 
>>> we do, pins will only be recorded in the Package.pins file when explicitly 
>>> set with swift package pin, and any pinned dependencies will not be updated 
>>> by the swift package update command; instead, they would need to be 
>>> unpinned to be updated. This would be a purely additive feature which 
>>> packages could use in addition to the resolved versions feature when 
>>> desired.
>>> 
>>> A new "resolved versions" feature will be added, which behaves very 
>>> similarly to how pinning previously behaved when autopinning was on. The 
>>> version of every resolved dependency will be recorded in a Package.resolved 
>>> file in the top-level package, and when this file is present in the 
>>> top-level package it will be used when performing dependency resolution, 
>>> rather than the package manager finding the latest eligible version of each 
>>> package. swift package updatewill update all dependencies to the latest 
>>> eligible versions and update the Package.resolved file accordingly.
>>> 
>>> Resolved versions will always be recorded by the package manager. Some 
>>> users may chose to add the Package.resolved file to their package's 
>>> .gitignore file. When this file is checked in, it allows a team to 
>>> coordinate on what versions of the dependencies they should use. If this 
>>> file is gitignored, each user will seperately choose when to get new 
>>> versions based on when they run the swift package update command, and new 
>>> users will start with the latest eligible version of each dependency. 
>>> Either way, for a package which is a dependency of other packages (e.g. a 
>>> library package), that package's Package.resolved file will not have any 
>>> effect on its client packages.
>>> 
>>> The existing swift package fetch command will be deprecated, removed from 
>>> the help message, and removed completely in a future release of the Package 
>>> Manager. In its place, a new swift package resolve command will be added. 
>>> The behavior of resolve will be to resolve dependencies, taking into 
>>> account the current version restrictions in the Package.swift manifest and 
>>> Package.resolved resolved versions file, and issuing an error if the graph 
>>> cannot be resolved. For packages which have previously resolved versions 
>>> recorded in the Package.resolved file, the resolvecommand will resolve to 
>>> those versions as long as they are still eligible. If the resolved versions 
>>> file changes (e.g. because a teammate pushed a new version of the file) the 
>>> next resolve command will update packages to match that file. After a 
>>> successful resolve command, the checked out versions of all dependencies 
>>> and the versions recorded in the resolved versions file will match. In most 
>>> cases the resolve command will perform no changes unless the 
>>> Package.swiftmanifest or Package.resolved file have changed.
>>> 
>>> The following commands will implicitly invoke the swift package resolve 
>>> functionality before running, and will cancel with an error if dependencies 
>>> cannot be resolved:
>>> 
>>> swift build
>>> swift test
>>> swift package generate-xcodeproj
>>> The swift package show-dependencies command will also implicitly invoke 
>>> swift package resolve, but it will show whatever information about the 
>>> dependency graph is available even if the resolve fails.
>>> 
>>> The swift package edit command will implicitly invoke swift package 
>>> resolve, but if the resolve fails yet did identify and fetch a package with 
>>> the package name the command supplied, the command will allow that package 
>>> to be edited anyway. This is useful if you wish to use the edit command to 
>>> edit version requirements and fix an unresolvable dependency graph. swift 
>>> package unedit will unedit the package and then perform a resolve.
>>> 
>>>  
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md#detailed-design>Detailed
>>>  design
>>> 
>>> The resolve command is allowed to automatically add new dependencies to the 
>>> resolved versions file, and to remove dependencies which are no longer in 
>>> the dependency graph. It can also automatically update the recorded 
>>> versions of any package whose previously-resolved version is no longer 
>>> allowed by the version requirements from the Package.swiftmanifests. When 
>>> changed version requirements force a dependency to be automatically 
>>> re-resolved, the latest eligible version will be chosen; any other 
>>> dependencies affected by that change will prefer to remain at their 
>>> previously-resolved versions as long as those versions are eligible, and 
>>> will otherwise update likewise.
>>> 
>>> The Package.resolved resolved versions file will record the git revision 
>>> used for each resolved dependency in addition to its version. In future 
>>> versions of the package manager we may use this information to detect when 
>>> a previously-resolved version of a package resolves to a new revision, and 
>>> warn the user if this happens.
>>> 
>>> The swift package resolve command will not actually perform a git fetch on 
>>> any dependencies unless it needs to in order to correctly resolve 
>>> dependencies. As such, if all dependencies are already resolved correctly 
>>> and allowed by the version constraints in the Package.swift manifest and 
>>> Package.resolved resolved versions file, the resolvecommand will not need 
>>> to do anything (e.g. a normal swift build won't hit the network or make 
>>> unnecessary changes during its implicit resolve).
>>> 
>>> If a dependency is in edit mode, it is allowed to have a different version 
>>> checked out than that recorded in the resolved versions file. The version 
>>> recorded for an edited package will not change automatically. If a swift 
>>> package updateoperation is performed while any packages are in edit mode, 
>>> the versions of those edited packages will be removed from the resolved 
>>> versions file, so that when those packages leave edit mode the next 
>>> resolution will record a new version for them. Any packages in the 
>>> dependency tree underneath an edited package will also have their resolved 
>>> version removed by swift package update, as otherwise the resolved versions 
>>> file might record versions that wouldn't have been chosen without whatever 
>>> edited package modifications have been made.
>>> 
>>>  
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md#alternatives-considered>Alternatives
>>>  considered
>>> 
>>> We considered repurposing the existing fetch command for this new behavior, 
>>> instead of renaming the command to resolve. However, the name fetch is 
>>> defined by git to mean getting the latest content for a repository over the 
>>> network. Since this package manager command does not always actually fetch 
>>> new content from the network, it is confusing to use the name fetch. In the 
>>> future, we may offer additional control over when dependency resolution is 
>>> allowed to perform network access, and we will likely use the word fetch in 
>>> flag names that control that behavior.
>>> 
>>> We considered continuing to write out the Package.pins file for packages 
>>> whose Swift tools version 
>>> <https://github.com/apple/swift-evolution/blob/master/proposals/0152-package-manager-tools-version.md>
>>>  was less than 4.0, for maximal compatibility with the Swift 3.1 tools. 
>>> However, as the old pinning behavior was a workflow feature and not a 
>>> fundamental piece of package compatibility, we do not consider it necessary 
>>> to support in the 4.0 tools.
>>> 
>>> We considered keeping the pin and unpin commands, with the new behavior as 
>>> discussed briefly in this proposal. While we think we may wish to bring 
>>> this feature back in the future, we do not consider it critical for this 
>>> release; the workflow it supports (updating all packages except a handful 
>>> which have been pinned) is not something most users will need, and there 
>>> are workarounds (e.g. specify an explicit dependency in the Package.swift 
>>> manifest).
>>> 
>>>  
>>> <https://github.com/rballard/swift-evolution/blob/e5e7ce76f29c855aa7162ed3733b09e701d662d6/proposals/NNNN-package-manager-revised-dependency-resolution.md#why-we-didnt-use-packagelock>Why
>>>  we didn't use "Package.lock"
>>> 
>>> We considered using the .lock file extension for the new resolved versions 
>>> file, to be consistent with many other package managers. We expect that the 
>>> decision not to use this extension will be controversial, as following 
>>> established precedent is valuable. However, we think that a "lockfile" is a 
>>> very poor name for this concept, and that using that name would cause 
>>> confusion when we re-introduce pins. Specifically:
>>> 
>>> Calling this a "lock" implies a stronger lockdown of dependencies than is 
>>> supported by the actual behavior. As a simple update command will reset the 
>>> locks, and a change to the specified versions in Package.swift will 
>>> override them, they're not really "locked" at all. This is misleading.
>>> When we re-introduce pinning, it would be very confusing to have both 
>>> "locks" and "pins". Having "resolved versions" and "pins" is not so 
>>> confusing.
>>> The term "lock" is already overloaded between POSIX file locks and locks in 
>>> concurrent programming.
>>> For comparison, here is a list of other package managers which implement 
>>> similar behavior and their name for this file:
>>> 
>>> Package Manager     Language        Resolved versions file name
>>> Yarn        JS      yarn.lock
>>> Composer    PHP     composer.lock
>>> Cargo       Rust    Cargo.lock
>>> Bundler     Ruby    Gemfile.lock
>>> CocoaPods   ObjC/Swift      Podfile.lock
>>> Glide       Go      glide.lock
>>> Pub Dart    pubspec.lock
>>> Mix Elixir  mix.lock
>>> rebar3      Erlang  rebar.lock
>>> Carton      Perl    carton.lock
>>> Carthage    ObjC/Swift      Cartfile.resolved
>>> Pip Python  requirements.txt
>>> NPM JS      npm-shrinkwrap.json
>>> Meteor      JS      versions
>>> Some arguments for using ".lock" instead of ".resolved" are:
>>> 
>>> Users of other package managers will already be familiar with the 
>>> terminology and behavior.
>>> For packages which support multiple package managers, it will be possible 
>>> to put "*.lock" into the gitignore file instead of needing a seperate entry 
>>> for "*.resolved".
>>> However, we do not feel that these arguments outweigh the problems with the 
>>> term "lock". If providing feedback asking that we reconsider this decision, 
>>> please be clear about why the above decision is incorrect, with new 
>>> information not already considered.
>>> 
>>> _______________________________________________
>>> swift-evolution mailing list
>>> swift-evolution@swift.org <mailto:swift-evolution@swift.org>
>>> https://lists.swift.org/mailman/listinfo/swift-evolution 
>>> <https://lists.swift.org/mailman/listinfo/swift-evolution>
> 

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