Loading GHC into GHCi (and ghcid)

[Michael Sloan]

Here is the diff adding ghci scripts and some related code changes:
https://phabricator.haskell.org/D4904

This has made development iterations drastically quicker for me, which
for me really lowers the friction to contribution.  All of my diffs in
the past week were developed by using ghc-in-ghci.

-Michael
On Wed, Jun 27, 2018 at 10:48 PM Michael Sloan <mgsloan at gmail.com> wrote:
>
> Wow!  This is an absolute game changer for me with regards to ghc
> development.  My usual workflow on large haskell projects is to use
> GHCI as much as possible for quick iterations.  I'm really glad
> Csongor figured this out and that you sent an email about it.
>
> I've been messing with this for a bit today, and after a few code
> changes, I can to load GHCI into GHCI!!  For example, I can modify
> "ghciWelcomeMessage", reload, and enter into the nested ghci:
>
> λ :r
> [491 of 492] Compiling GHCi.UI          ( ../ghc/GHCi/UI.hs, tmp/GHCi/UI.o )
> Ok, 492 modules loaded.
> λ :main -ignore-dot-ghci --interactive
> GHCi inception, version 8.7.20180627: http://www.haskell.org/ghc/  :? for help
> Prelude> unwords ["it", "works!"]
> "it works!"
> Prelude> :q
> Leaving GHCi.
> λ Prelude.unwords ["now,", "in", "outer", "GHCi"]
> "now, in outer GHCi"
>
> I will be opening up a PR soon that makes this convenient, once I've
> polished it up.
>
> -Michael
> On Wed, May 30, 2018 at 1:43 PM Matthew Pickering
> <matthewtpickering at gmail.com> wrote:
> >
> > Hi all,
> >
> > Csongor has informed me that he has worked out how to load GHC into
> > GHCi which can then be used with ghcid for a more interactive
> > development experience.
> >
> > 1. Put this .ghci file in compiler/
> >
> > https://gist.github.com/mpickering/73749e7783f40cc762fec171b879704c
> >
> > 2. Run "../inplace/bin/ghc-stage2 --interactive -odir tmp -hidir tmp"
> > from inside compiler/
> >
> > It may take a while and require a little bit of memory but in the end
> > all 500 or so modules will be loaded.
> >
> > It can also be used with ghcid.
> >
> > ghcid -c "../inplace/bin/ghc-stage2 --interactive -odir tmp -hidir tmp"
> >
> > Hopefully someone who has more RAM than I.
> >
> > Can anyone suggest the suitable place on the wiki for this information?
> >
> > Cheers,
> >
> > Matt
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