[Haskell-beginners] How to install new GHC ?

Tue Dec 12 14:33:13 UTC 2017

@Michael Snoyman:

I returned back all .cabal-files and added compiler: ghc-8.2.2, `stack build`
printed out this:

---cut---
  Error: While constructing the build plan, the following exceptions were encountered:

  In the dependencies for Cabal-1.24.2.0:
      process-1.6.1.0 from stack configuration does not match >=1.1.0.1 && <1.5 (latest matching version is 1.4.3.0)
  needed due to my-common-utils-0.2.0.0 -> Cabal-1.24.2.0

  In the dependencies for versions-3.1.1:
      base-4.10.1.0 from stack configuration does not match >=4.8 && <4.10 (latest matching version is 4.9.1.0)
  needed due to my-common-utils-0.2.0.0 -> versions-3.1.1

  Some potential ways to resolve this:

    * Recommended action: try adding the following to your extra-deps in /home/pavel/prj/automation/revcompl-mon/stack.yaml:

  - base-4.9.1.0
  - process-1.4.3.0

    * Set 'allow-newer: true' to ignore all version constraints and build anyway.

    * You may also want to try using the 'stack solver' command.

  Plan construction failed.
---cut---

After adding "allow-newer: true" build process starts, all looked fine until:

   .../SimpleTagging.hs:281:51: error:
        • Couldn't match type ‘Type’ with ‘DerivClause’
          Expected type: [DerivClause]
            Actual type: [Type]
        • In the sixth argument of ‘DataD’, namely ‘derivs'’
          In the expression: DataD [] ty' tyVars Nothing newCs derivs'
          In the first argument of ‘(++)’, namely
            ‘[DataD [] ty' tyVars Nothing newCs derivs']’
        |
    281 |       return $ [DataD [] ty' tyVars Nothing newCs derivs'] ++ showInst
        |                                                   ^^^^^^^

which IMHO means that TemplateHaskell ("API") was changed from 8.0.2 to
8.2.2 because the same code is compiling with old GHC 8.0.2.

> Hi Paul,
> 
> A Stackage snapshot specifies both a GHC version and a set of
> packages. Stackage snapshots are built and tested to ensure that the
> packages are compatible. While you could tell Stack to use a
> different GHC version with a snapshot[1], this is unlikely to work,
> since GHC major releases usually break some packages.
> 
> I think everyone who's trying to help you (both with Cabal and Stack
> workflows) would be able to do so better if you explain which package
> you're trying to use which is no longer available in Stackage
> Nightly. In some cases, you can simply add it as an extra
> dependencies for Stack (e.g., `extra-deps: [acme-missiles-0.3]`),
> while in others there is some inherent incompatibility.
> 
> Right now, you'll just be getting guesses about how to theoretically
> get some unknown package to build with a bunch of others.
> 
> Michael
> 
> [1] Using a setting like `compiler: ghc-8.2.2`
> 
> On Tue, Dec 12, 2017 at 3:43 PM, Baa <aquagnu at gmail.com> wrote:
> 
> > @David: I tried to switch to nightly but in project's .yaml file and
> > got error about missing of some library (as I understand, it is
> > missing in last nightly). So, if I try to do it through .yaml file
> > then how to use new GHC (8.2.2) but with LTS for 8.0.2? Is it
> > possible? I need last stable LTS where all libraries (using in the
> > projects) exist, but with new GHC 8.2.2 which is too new for stable
> > LTS. As I read somewhere, GHC version and Stackage version are
> > linked together hardly in stack tool, or?
> >  
> > > You can see how to configure stack here:
> > > https://github.com/commercialhaskell/stack/blob/release/doc/yaml_  
> > configuration.md  
> > >
> > > The short of it is that to have stack ghci choose a particular
> > > version of ghc, you probably need to modify
> > > ~/.stack/global/stack.yaml, change resolver to something here
> > > https://www.stackage.org/snapshots that has your version of ghc
> > > and dependencies similar to what your project wants.  For example
> > > 'nightly-2017-12-10'.
> > >
> > > On Tue, Dec 12, 2017 at 7:53 AM, Baa <aquagnu at gmail.com> wrote:
> > >  
> > > > @Francesco: unfortunately nightly misses some package. So, I
> > > > tried:
> > > >
> > > >   $ stack --resolver=ghc-8.2.2 setup --reinstall
> > > >   Preparing to install GHC (tinfo6) to an isolated location.
> > > > This will not interfere with any system-level installation.
> > > > Already downloaded. Installed GHC.
> > > >
> > > >   stack will use a sandboxed GHC it installed
> > > >   For more information on paths, see 'stack path' and 'stack
> > > > exec env' To use this GHC and packages outside of a project,
> > > > consider using: stack ghc, stack ghci, stack runghc, or stack
> > > > exec
> > > >
> > > > So seems that 8.2.2 was installed, right? But how to build the
> > > > project with new GHC now? I never used cabal before, `stack
> > > > ghci` still runs 8.0.2 instead of 8.2.2. Installed GHC 8.2.2
> > > > does not correspond to .yaml file LTS - maybe this is a reason
> > > > why old 8.0.2 is stil used...
> > > >
> > > > When I try cabal build/new-build/repl I get:
> > > >
> > > >   cabal: The program 'ghc' version >=6.4 is required but it
> > > > could not be found.
> > > >
> > > > So, cabal does not know about installed GHC versions (at least
> > > > 8.0.2, used by stack). I tried --require-sandbox but without
> > > > success.
> > > >
> > > >  
> > > > > On Tue, Dec 12, 2017 at 01:56:03PM +0200, Baa wrote:  
> > > > > > Would somebody explain me what is wrong here and how I can
> > > > > > test a project with new 8.2.2 GHC?  
> > > > >
> > > > > Hello Paul, I don't think stack lts has 8.2.2 just yet. Use a
> > > > > nightly or download/install ghc from here and compile your
> > > > > project with the new `cabal new-build`.
> > > > >
> > > > > [1]
> > > > > https://www.haskell.org/ghc/download_ghc_8_2_2.html#binaries
> > > > >
> > > > >
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> > > >
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