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

Wed Sep 14 15:54:46 UTC 2016

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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> >> >> > 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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> >> >> 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
> >> _______________________________________________
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> >> Haskell-community at haskell.org
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> >
> >
>
>
>
> --
> Chris Allen
> Currently working on http://haskellbook.com
>
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