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

Wed Sep 14 15:59:14 UTC 2016

I don't think anyone thinks it's bad to have a --with-ghc option, AFAIK the
only reason it hasn't been done is lack of desire/time, since it's an
uncommon workflow. Unlike with cabal, the normal way to specify a different
GHC is with the `--resolver` setting. AFAIK, this flag could be added.

On Wed, Sep 14, 2016 at 6:54 PM, Simon Marlow <marlowsd at gmail.com> wrote:

> But what if I don't want to fiddle with my PATH?  Why is it so bad for
> stack to have a --with-ghc option to tell it what GHC to use?
>
> On 14 September 2016 at 16:23, Christopher Allen <cma at bitemyapp.com>
> wrote:
>
>> 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.
>> >> >> >
>> >> >> > _______________________________________________
>> >> >> > Haskell-Cafe mailing list
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>> >> >> > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
>> >> >> > Only members subscribed via the mailman list are allowed to post.
>> >> >>
>> >> >> --
>> >> >> Chris Allen
>> >> >> Currently working on http://haskellbook.com
>> >> >> _______________________________________________
>> >> >> Haskell-Cafe mailing list
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>> >> >> Only members subscribed via the mailman list are allowed to post.
>> >>
>> >>
>> >>
>> >> --
>> >> Chris Allen
>> >> Currently working on http://haskellbook.com
>> >> _______________________________________________
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>> >> Haskell-community at haskell.org
>> >> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-community
>> >
>> >
>>
>>
>>
>> --
>> Chris Allen
>> Currently working on http://haskellbook.com
>>
>
>
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