[Haskell-cafe] [Haskell-community] technical thoughts on stack

Wed Sep 14 15:23:05 UTC 2016

Probably pretty similarly to how we use patched GHCJS at work with Stack.

-- from the stack.yaml
system-ghc: true
compiler: ghcjs-0.2.0_ghc-7.10.2
resolver: ghcjs-0.2.0_ghc-7.10.2

-- in the Makefile
ghcjs:
    git clone https://github.com/myorg/ghcjs
    cd ghcjs && stack setup && stack install
    cd ghcjs && stack install cabal-install alex happy
    cd ghcjs && stack exec -- ghcjs-boot --dev --no-haddock

It's just picking GHCJS up from the path, with system-ghc: true, we're
telling it that is kosher.

We disable system-ghc usage for regular GHC projects, it makes
profiling less convenient than if you use a Stack managed GHC but if
you're doing GHC dev the difference means nothing.

On Wed, Sep 14, 2016 at 9:42 AM, Simon Marlow <marlowsd at gmail.com> wrote:
> How would I use stack with a GHC 8.0.2 release candidate?
>
> On 13 September 2016 at 21:27, Christopher Allen <cma at bitemyapp.com> wrote:
>>
>> Stack is not your shell, a build script, or a Makefile. It already has
>> path management for the GHC installations it provisions and supports.
>> It is not Stack's job to mutilate your path to support external GHC
>> installations.
>>
>> Make a Makefile or add shortcuts to your bashrc to switch compilers.
>>
>> On Tue, Sep 13, 2016 at 3:16 PM, Paolo Giarrusso <p.giarrusso at gmail.com>
>> wrote:
>> > On Tuesday, September 13, 2016 at 10:05:44 PM UTC+2, Christopher Allen
>> > wrote:
>> >>
>> >> Stack users are moving away from enabling system installed GHCs by
>> >> default because it breaks the ease of enabling profiling for libraries
>> >> when you're using a Stack-installed GHC.
>> >
>> >
>> >>
>> >> I'm not sure why multiple system-installed GHCs needs to be supported
>> >> in addition to the GHC support Stack already provides. That's extra
>> >> work for...what? Stack isn't trying to compete with Nix. It's more
>> >> like a blend of rustup and cargo -- or Clojure's Leiningen.
>> >
>> >
>> > To clarify: I'm not proposing stack to install those GHCs, just to use
>> > them.
>> >
>> > I think the extra work would be limited (calling GHC-X.Y.Z instead of
>> > GHC)
>> > and has other technical advantages
>> > (https://github.com/commercialhaskell/stack/issues/2433). Mind you, I'm
>> > willing to contribute the work and not asking anybody—I've just been
>> > busy.
>> >
>> > Right now I have to modify the PATH every time I use GHC 7.8.4 because I
>> > needed to customize the build (I'm on OS X 10.11), but I still want GHC
>> > 8 by
>> > default.
>> >
>> >>
>> >> On Tue, Sep 13, 2016 at 3:01 PM, Paolo Giarrusso <p.gia... at gmail.com>
>> >> wrote:
>> >> >
>> >> >
>> >> > On Tuesday, September 13, 2016 at 9:47:20 PM UTC+2, Richard Eisenberg
>> >> > wrote:
>> >> >>
>> >> >> Thanks, many, for explaining better ways to interact directly with
>> >> >> GHC
>> >> >> after using a `stack setup`. Perhaps, then, all that’s stopping
>> >> >> someone
>> >> >> like
>> >> >> me from liking the ease of `stack setup` is a little missing PR (as
>> >> >> in,
>> >> >> public relations). I understand that many people want to keep GHC
>> >> >> cloistered
>> >> >> away to ease version swapping, but others (like me) want GHC
>> >> >> available
>> >> >> front
>> >> >> and center.
>> >> >>
>> >> >> Other minor points:
>> >> >> `stack env` does not work for me: my version of stack does not know
>> >> >> how
>> >> >> to
>> >> >> `env`.
>> >> >
>> >> >
>> >> > That's correct—stack env was a feature request.
>> >> >
>> >> > The warning on `stack ghci` doesn't happen usually, but I'd say
>> >> > that's a
>> >> > bug
>> >> > (probably because it's a new install)?
>> >> >
>> >> > I use stack (and have contributed a bit recently), but I agree
>> >> > there's a
>> >> > few
>> >> > things stack could do better for this workflow.
>> >> >
>> >> > And the transition has a rather annoying learning curve—stack ghci
>> >> > and
>> >> > stack
>> >> > ghc are not the same as ghci/ghc. I think that's on purpose to
>> >> > support a
>> >> > project-based workflow, and it has upsides, but it's a transition
>> >> > pitfall.
>> >> >  Lots of things *are* explained in
>> >> > https://docs.haskellstack.org/en/latest/faq/, but you do need learn a
>> >> > few
>> >> > things from scratch.
>> >> >
>> >> > You want stack exec ghc and stack exec ghci, and arbitrary options
>> >> > require a
>> >> > double dash `--` — use `stack ghc -- --version` or `stack exec -- ghc
>> >> > --version`. And I'm afraid the command syntax is mostly frozen by
>> >> > now.
>> >> >
>> >> > To support a compiler-based workflow, there are a few things
>> >> > planned—I
>> >> > opened an issue to collect them, starting from Simon Marlow's recent
>> >> > email:
>> >> > https://github.com/commercialhaskell/stack/issues/2546
>> >> >
>> >> > BTW, a system-installed GHC already works if you stick to one (and
>> >> > only
>> >> > build projects that need that). But I'd love to support multiple
>> >> > system-installed GHCs and being able to pick the one you need.
>> >> >
>> >> > As others already explained, giving access to stack-installed GHCs
>> >> > can
>> >> > be
>> >> > problematic—they're going to work, in part, exactly because you can't
>> >> > install in their package database.
>> >> >
>> >> > Having stack install system-wide GHCs would IMHO risk opening a can
>> >> > of
>> >> > worms—having working binaries for all Linux distros requires some
>> >> > work,
>> >> > system installers would be harder and most users would dislike them.
>> >> >
>> >> > _______________________________________________
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>> >>
>> >> --
>> >> Chris Allen
>> >> Currently working on http://haskellbook.com
>> >> _______________________________________________
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>>
>>
>>
>> --
>> Chris Allen
>> Currently working on http://haskellbook.com
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>
>

-- 
Chris Allen
Currently working on http://haskellbook.com