Drop into a nix shell with ghcHEAD

[Matthew Pickering]

I have now added a small wrapper script which allows you to pull
artefacts by MR number.

https://github.com/mpickering/ghc-artefact-nix#ghc-head-from-script

```
# Fetches MR 180
ghc-head-from 180
```

```
#Fetches ghc/master
ghc-head-from
```

The most convenient way to access the script is to add the attribute
`nur.repos.mpickering.ghc-head-from` to your configuration.nix.

Cheers,

Matt

On Tue, Jan 22, 2019 at 2:49 PM Matthew Pickering
<matthewtpickering at gmail.com> wrote:
>
> I just extended it slightly so you can grab artifacts from MRs as
> well. The interface is not perfect but should still be useful.
>
> https://github.com/mpickering/ghc-artefact-nix
>
> You can specify the two options `fork` and `branch` in order to download
> an artefact for a contributors branch in order to test a merge request. For
> example in order to test
> [!180](https://gitlab.haskell.org/ghc/ghc/merge_requests/180) which
> is on the fork called `brprice` and from branch `wip/doc-pragma-fixes`
> I can run:
>
> ```
> nix run -f https://github.com/mpickering/ghc-artefact-nix/archive/master.tar.gz
> \
>       --argstr fork brprice \
>       --argstr branch wip/doc-pragma-fixes \
>       ghcHEAD cabal-install
> ```
>
> On Thu, Jan 17, 2019 at 3:49 AM chessai . <chessai1996 at gmail.com> wrote:
> >
> > Beautiful. Thanks for sharing
> >
> > On Wed, Jan 16, 2019 at 9:34 AM Matthew Pickering <matthewtpickering at gmail.com> wrote:
> >>
> >> Hi all,
> >>
> >> I have written a devastating new script which makes it easy to test
> >> snippets and packages with build artefacts built by the gitlab CI. One
> >> invocation of `nix-shell` will enter an environment with the most
> >> recent build artefact from master.
> >>
> >> Usage:
> >>
> >> ```
> >> > nix-shell https://github.com/mpickering/ghc-artefact-nix/archive/master.tar.gz
> >> unpacking 'https://github.com/mpickering/ghc-artefact-nix/archive/master.tar.gz'...
> >> <lots more output>
> >> > ghc --version
> >> The Glorious Glasgow Haskell Compilation System, version 8.7.20190115
> >> ```
> >>
> >> Repo: https://github.com/mpickering/ghc-artefact-nix
> >>
> >> So far we have tested it works on NixOS and darwin but support for
> >> other platforms that nix supports and we build artefacts for should be
> >> easy. It might already work on i386 and aarch64 as well but I didn't
> >> test these.
> >>
> >> Cheers,
> >>
> >> Matt
> >> _______________________________________________
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> >> ghc-devs at haskell.org
> >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs