Re: Type-level error messages

Iavor Diatchki writes:

Hello,

Hello! Very good timing on the message; we just finished discussing your work not more than an hour ago. You can disregard my message; I didn't notice yours before sending it.

On Thu, Oct 22, 2015 at 9:47 AM, Simon Peyton Jones wrote:

...

I’ve forgotten the state of your type-level error messages work. How’s it going?

I think we should try to add it to 8.0.1. The current status is that the idea is implemented on a branch. Then, there were some comments and suggestions that maybe we should do things in a different way, implementation wise. I haven't had a chance to look into these in detail, or implement them, and as far as I know nobody else has stepped up to make the changes. So we could simply go with the current version, and if for some reason we want to change the implementation we could do it later, as I don't think the API will be affected in any way. When do the changes need to happen by, so that it makes it in 8.0? I have been a bit busy, but I could probably find some time to make whatever changes are required for this to be merged.

OK good! In that case

· Add it to the hoped-for features in the GHC 8.01. status page

Where is the GHC 8.01 status page?

Here, https://ghc.haskell.org/trac/ghc/wiki/Status/GHC-8.0.1

· Write a wiki page with a specification

...

Here is the specification:

https://ghc.haskell.org/trac/ghc/wiki/CustomTypeErros

Great! I have moved this to, https://ghc.haskell.org/trac/ghc/wiki/Proposal/CustomTypeErrors and left a redirect page in the old location. Is there a Trac ticket for this?

...

· Announce the proposal and seek feedback

We already had a discussion about it, there are notes on the wiki. I don't think any of the comments were about the actual design, the comments seem to be more about the implementation. On that front, if I am to make the necessary changes, maybe we could have a chat (or e-mail conversation) to make sure that I understand the changes and the motivation for them---the wiki is not a great media for question/answer type of discussions.

I'll let you and Simon work this out.

...

· Meanwhile make sure the branch reflects what you want to be in it

I think that the branch should be in an OK state, except that it is not merged with the latest HEAD.

Where can this branch be found? Cheers, - Ben