Hi all,
I've should have CCed cabal-devel on this discussion from the start.
My apologies. I will try to remember to have all these discussion in
the open in the future.
We're discussing how the sandbox mechanism that cabal got during this
year's GSoC should be exposed to users. I've included the discussion
so far below:
--8<-----------------------
Date: Fri, 24 Aug 2012 15:40:14 -0700
Subject: Agreeing on a UI for sandboxes
From: Johan Tibell <johan.tib...@gmail.com>
To: Duncan Coutts <duncan.cou...@googlemail.com>,
=?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>,
Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
Hi all,
I've now merged Mikhail's last patches and the remaining work is to
figure out how to expose the sandbox mechanism to users in a way that
easy to understand and convenient to use. Mikhail has added some
hidden commands that you can use to today to work within the sandbox.
The goal is to remove these commands in favor of modifying the
behavior of the current command set. If we could bring out the
different possible designs and issues before ICFP, perhaps we can
solve any remaining issues in person there.
Mikhail, as a starting point, could you please explain how you'd use
these hidden commands (you can probably reuse your description from
the pull request).
-- Johan
--8<-----------------------
Date: Sat, 25 Aug 2012 01:01:04 +0200
Subject: Re: Agreeing on a UI for sandboxes
From: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
To: Johan Tibell <johan.tib...@gmail.com>
Cc: Duncan Coutts <duncan.cou...@googlemail.com>,
=?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>
Hi all,
On Sat, Aug 25, 2012 at 12:40 AM, Johan Tibell <johan.tib...@gmail.com> wrote:
> Mikhail, as a starting point, could you please explain how you'd use
> these hidden commands (you can probably reuse your description from
> the pull request).
There are four new hidden commands:
* cabal sandbox-configure
Same as 'cabal configure', but also initialises a new sandbox to be
used for building.
* cabal sandbox-add-source
Makes a source package available for installation inside the sandbox.
* cabal sandbox-build
Builds a package inside the sandbox.
* cabal sandbox-install
Installs a package into the sandbox.
I tried to keep the UI close to the current one, so dependency
installation & configuration is still done manually. If a dependency
added with sandbox-add-source is updated, it must be manually
reinstalled with cabal sandbox-install LibName.
Here's an example session:
$ git clone git://github.com/haskell/cabal.git
$ cd cabal/cabal-install
$ cabal sandbox-configure -w /path/to/ghc-7.4.1
$ cabal sandbox-add-source ../Cabal
$ cabal sandbox-install --only-dependencies
# Since the previous configure only initialised the sandbox
$ cabal sandbox-configure -w /path/to/ghc-7.4.1
$ cabal sandbox-build
One major annoyance with the current UI is that you often have to run
cabal sandbox-configure twice (first to initialise the sandbox, and
after that to actually configure the package once the dependencies
have been installed). I propose that we make sandbox-configure run
'sandbox-install --only-dependencies' automatically after creating a
sandbox.
--8<-----------------------
Date: Mon, 27 Aug 2012 20:28:29 +0200
Message-ID: <caljd_v5v8uwmfblwdxdi-wxt-p+tkmhcgs518wcuycqa2p1...@mail.gmail.com>
Subject: Re: Agreeing on a UI for sandboxes
From: =?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>
To: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
Cc: Johan Tibell <johan.tib...@gmail.com>, Duncan Coutts
<duncan.cou...@googlemail.com>
Hi.
> I tried to keep the UI close to the current one, so dependency
> installation & configuration is still done manually. If a dependency
> added with sandbox-add-source is updated, it must be manually
> reinstalled with cabal sandbox-install LibName.
You mean a sandbox-install command to something depending on LibName
won't pick it up?
> Here's an example session:
>
> $ git clone git://github.com/haskell/cabal.git
> $ cd cabal/cabal-install
> $ cabal sandbox-configure -w /path/to/ghc-7.4.1
So I can only create a sandbox in a Cabal package directory? And
"cabal sandbox-add-source ." is implicit?
> $ cabal sandbox-add-source ../Cabal
> $ cabal sandbox-install --only-dependencies
Why can't I just say "cabal sandbox-install" at this point?
> # Since the previous configure only initialised the sandbox
> $ cabal sandbox-configure -w /path/to/ghc-7.4.1
> $ cabal sandbox-build
>
> One major annoyance with the current UI is that you often have to run
> cabal sandbox-configure twice (first to initialise the sandbox, and
> after that to actually configure the package once the dependencies
> have been installed). I propose that we make sandbox-configure run
> 'sandbox-install --only-dependencies' automatically after creating a
> sandbox.
I'm not particularly fond of having non-install commands download
stuff from the internet.
Cheers,
Andres
--8<-----------------------
Date: Tue, 28 Aug 2012 03:51:59 +0200
Subject: Re: Agreeing on a UI for sandboxes
From: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
To: =?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>
Cc: Johan Tibell <johan.tib...@gmail.com>, Duncan Coutts
<duncan.cou...@googlemail.com>
Hi,
On Mon, Aug 27, 2012 at 8:28 PM, Andres L=F6h <andres.l...@googlemail.com> =
wrote:
> Hi.
>
>> I tried to keep the UI close to the current one, so dependency
>> installation & configuration is still done manually. If a dependency
>> added with sandbox-add-source is updated, it must be manually
>> reinstalled with cabal sandbox-install LibName.
>
> You mean a sandbox-install command to something depending on LibName
> won't pick it up?
Not if the same version is already installed. We can change it so all
dependencies added with add-source are always reinstalled when you run
sandbox-install.
I'm not quite satisfied with both the current and the proposed
solution, ideally it'd possible to detect when some .hs files have
changed and the package needs to be reinstalled.
>> Here's an example session:
>>
>> $ git clone git://github.com/haskell/cabal.git
>> $ cd cabal/cabal-install
>> $ cabal sandbox-configure -w /path/to/ghc-7.4.1
>
> So I can only create a sandbox in a Cabal package directory?
There is a --sandbox option that lets you specify the location (so
shared sandboxes are allowed).
> And
> "cabal sandbox-add-source ." is implicit?
This is not currently being done, but is probably worth adding (to
support shared sandboxes better).
>> $ cabal sandbox-add-source ../Cabal
>> $ cabal sandbox-install --only-dependencies
>
> Why can't I just say "cabal sandbox-install" at this point?
You can use sandbox-install once the sandbox has been created, it's
just that I opted to use sandbox-build in the example.
> I'm not particularly fond of having non-install commands download
> stuff from the internet.
Good point, I'm also a bit uneasy about this. On the other hand,
running 'sandbox-install --only-dependencies' directly after creating
a sandbox is a common use case. I also don't like requiring the user
to run 'sandbox-configure' twice. Maybe the sandbox should be
initialised by install instead of configure?
--8<-----------------------
Date: Tue, 28 Aug 2012 08:28:47 +0200
Subject: Re: Agreeing on a UI for sandboxes
From: =?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>
To: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
Cc: Johan Tibell <johan.tib...@gmail.com>, Duncan Coutts
<duncan.cou...@googlemail.com>
Hi.
>> You mean a sandbox-install command to something depending on LibName
>> won't pick it up?
>
> Not if the same version is already installed.
Ah, ok. But if the version changes, it will. That makes sense. The
other point would be fixed if the other GSoC project gets closer to
maturity.
> We can change it so all
> dependencies added with add-source are always reinstalled when you run
> sandbox-install.
I wouldn't change it yet. If at all, it should be a flag per
add-source. Not everything you add-source are libraries you
necessarily actively develop at the time. And I guess you can
add-source not only local packages, right?
> I'm not quite satisfied with both the current and the proposed
> solution, ideally it'd possible to detect when some .hs files have
> changed and the package needs to be reinstalled.
Yes, indeed.
>> So I can only create a sandbox in a Cabal package directory?
>
> There is a --sandbox option that lets you specify the location (so
> shared sandboxes are allowed).
Cool.
>> And
>> "cabal sandbox-add-source ." is implicit?
>
> This is not currently being done, but is probably worth adding (to
> support shared sandboxes better).
>
>>> $ cabal sandbox-add-source ../Cabal
>>> $ cabal sandbox-install --only-dependencies
>>
>> Why can't I just say "cabal sandbox-install" at this point?
>
> You can use sandbox-install once the sandbox has been created, it's
> just that I opted to use sandbox-build in the example.
Yes, but that's what makes you end up having to run sanbox-configure twice.
>> I'm not particularly fond of having non-install commands download
>> stuff from the internet.
>
> Good point, I'm also a bit uneasy about this. On the other hand,
> running 'sandbox-install --only-dependencies' directly after creating
> a sandbox is a common use case. I also don't like requiring the user
> to run 'sandbox-configure' twice. Maybe the sandbox should be
> initialised by install instead of configure?
That seems to be more in line with how it works without sandbox-* ?
Cheers,
Andres
--8<-----------------------
Date: Tue, 28 Aug 2012 16:55:46 +0200
Subject: Re: Agreeing on a UI for sandboxes
From: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
To: =?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>
Cc: Johan Tibell <johan.tib...@gmail.com>, Duncan Coutts
<duncan.cou...@googlemail.com>
Hi,
On Tue, Aug 28, 2012 at 8:28 AM, Andres L=F6h <andres.l...@googlemail.com> =
wrote:
> Ah, ok. But if the version changes, it will. That makes sense. The
> other point would be fixed if the other GSoC project gets closer to
> maturity.
Looking forward to that!
> I wouldn't change it yet. If at all, it should be a flag per
> add-source. Not everything you add-source are libraries you
> necessarily actively develop at the time.
We discussed this - the initial idea was to have a separate
link-source command. Johan thinks that it is redundant and it would be
best to avoid adding it.
One idea is to make 'install' run 'cabal build' on packages added with
add-source (those that we depend on) and then only install those files
that have actually changed (so that re-linking is avoided).
> And I guess you can
> add-source not only local packages, right?
The plan is to allow linking to remote repositories. This is not yet
implemented.
>>> I'm not particularly fond of having non-install commands download
>>> stuff from the internet.
>>
>> Good point, I'm also a bit uneasy about this. On the other hand,
>> running 'sandbox-install --only-dependencies' directly after creating
>> a sandbox is a common use case. I also don't like requiring the user
>> to run 'sandbox-configure' twice. Maybe the sandbox should be
>> initialised by install instead of configure?
>
> That seems to be more in line with how it works without sandbox-* ?
Kind of. I think that I'll make sandbox-install initialise a sandbox
by default because of this use case:
$ mkdir darcs && cd darcs
$ cabal sandbox-install darcs
But using 'install' for building feels inconsistent. For the normal
build you are using 'cabal configure && cabal install
--only-dependencies && cabal build'. For the sandboxed build you would
be using 'cabal install --sandbox'.
Ideally, I'd like the differences between workflows to be minimal.
Assuming that the standard commands were made sandbox-aware:
$ cabal configure --sandbox
$ cabal install --only-dependencies
$ cabal build
But configure fails when the sandbox is empty, so one has to run it twice.
--8<-----------------------
Date: Tue, 28 Aug 2012 16:45:55 -0700
Subject: Re: Agreeing on a UI for sandboxes
From: Johan Tibell <johan.tib...@gmail.com>
To: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>
Cc: =?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>,
Duncan Coutts <duncan.cou...@googlemail.com>
Hi,
I haven't had time to collect my thoughts fully yet, so here are some
initial thoughts:
It's important that users don't use a mix of sandbox and non-sandbox
commands by misstake. That would lead to confusing build errors.
Ideally the users should request that work is to be done in a sandbox
once and then all commands should use the sandbox. This means that
there should be no e.g. cabal build/test/bench --sandbox flags.
Perhaps a separate command, cabal init-sandbox, would be the best
approach. Running that command would create the right package
environment for running in a sandbox and the remaining commands would
then use that sandbox. Separating init-sandbox from configure prevents
the user from removing the sandbox preference when reconfiguring for
some other reason (e.g. to add --enable-tests). To get out of the
sandbox the user would edit the package environment file.
Alternatively we could have a sandbox command that lets you both add
and remove sandboxes.
cabal sandbox --init
cabal sandbox --delete
cabal sandbox --init --path=/path/to/sandbox
-- Johan
--8<-----------------------
Date: Tue, 28 Aug 2012 16:56:20 -0700
Subject: Re: Agreeing on a UI for sandboxes
From: Johan Tibell <johan.tib...@gmail.com>
To: =?ISO-8859-1?Q?Andres_L=F6h?= <andres.l...@googlemail.com>
Cc: Mikhail Glushenkov <the.dead.shall.r...@gmail.com>,
Duncan Coutts <duncan.cou...@googlemail.com>
On Mon, Aug 27, 2012 at 11:28 PM, Andres L=F6h <andres.l...@googlemail.com>=
wrote:
>> We can change it so all
>> dependencies added with add-source are always reinstalled when you run
>> sandbox-install.
>
> I wouldn't change it yet. If at all, it should be a flag per
> add-source. Not everything you add-source are libraries you
> necessarily actively develop at the time. And I guess you can
> add-source not only local packages, right?
I'm worried about making cabal even more cumbersome to use. Today you
need to do the following to work on several repos at once:
for every dependency:
cd $dir
cabal configure
cabal build
cd $main-dir
cabal configure --package-db=3D$dir1/dist/package.conf.inplace
--package-db=3D$dir1/dist/package.conf.inplace ...
If the use manually has to rebuild dependencies every time the change
even when using a sandbox we have essentially no improvement over
status quo and or cabal-dev.
Cabal today is too much about mechanism and not enough about user
intentions. Lets try to move it towards the latter, not away from it.
Here's my claim, if rebuilding my project requires something more than
"cabal build", we did something wrong in designing the user interface.
-- Johan
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