Re: Newcomers' Guide to GHC Development

On Thu, Feb 28, 2019 at 12:43:12PM +0100, Spiwack, Arnaud wrote:

- The dependencies instruction are too complex and long-winded. I'd start by: if you are a nix user, use , otherwise you need <all this> installed [in particular, no sectioning of the dependencies!], see <the relevant place> to find instruction for your particular system.

One consideration with this guide is that we want to reduce the amount of indirection - the current "getting started" guide is very close to being just a chaotic collection of links, and if you follow them all to exhaustion, you will get lost and confused long before you manage to make your first successful build (I know I did). So we decided to keep the main narrative entirely in this document, providing links to other pages and resources only for optional steps or unusual situations. The nix-based setup is certainly a good idea though, and I do agree that shortening this section further would be a good thing, so I will definitely look into it again. Please keep in mind however that we cannot possibly cater to all potential needs; we need to strike a balance.

- The considerations about gitlab are mostly trivial and distract from the point (at this point we're trying to build GHC): simply give a git clone instruction from the main repository.

This was originally in the document; however, the goal here is not just to build GHC (there are separate instructions for that), but to actually issue a MR, and for that, you are supposed to create a fork. So we instruct people to do that right away, and then clone the fork, rather than clone the main repo and then modify their working copy to point to the fork later.

(also highlight the fact that there is a `--recursive`, it's easily missed, and give the `git submodule update --init` back up in case it was forgotten, maybe?)

Makes sense, I will add that.

- Scrap the section called A note on Hadrian. It will just come up as scary. The further reading section is sufficient to point to Hadrian issues

The purpose of this is not to scare people off, but to avoid confusion when running into unexpected issues. Hadrian *is* a complex beast, and quite new, and experience shows that people still encounter issues. The intended message here is "if it doesn't work, it may not be your fault". I will reword.

- devel2 is a good default flavour, but, when it comes up, you should also include a link to a documentation that says: want to do X -> use flavour Y

In the interest of keeping things short, I'm inclined to say let's not do that, and rely on the links we're already providing. (Those do not work properly from within the github rendering of this page, but will be fine if viewed from within gitlab; you should also be able to figure out what the corresponding wiki pages on the old Trac wiki are).

- The idiom/stages seems to be a dead link, but maybe it'll work when this document is transferred to the wiki?

Yes, it should. I have pushed this page to a development gitlab instance, and the link seems to work fine there. See above.

- `git clean` is not sufficient to get to a pristine state, you need `git clean -xdf && git submodule foreach 'git clean -xdf'`. It's probably even better to just give the following one-liner: `git clean -xdf && git submodule foreach 'git clean -xdf' && git submodule update --init`. Maybe even even better, build.hs could have an option to call this one-liner?

Not a fan of tying SCM concerns into the build system. Rest seems reasonable, although choice of git clean details may be up to the individual (e.g. -f vs. -i). Anyhow, thanks a lot for your feedback.