Scoped Type Variables discussion forum [was: open up the issues tracker on ghc-proposals]

Anthony Clayden anthony_clayden at
Sat May 5 02:34:38 UTC 2018

This thread is a discussion about discussions, not the discussion itself ;-)

I'm cc'ing to the cafe; but I'd prefer replies to come to

>> I can volunteer to at least scrape together all the objections to
ScopedTypeVariables as currently. It's not yet a proposal, so not on
github. Start a wiki page? A cafe thread? (It'll get lost.) A ghc-users
thread? (It'll get ignored.)

> ... don’t care what forums or list or whatever. As long as it’s collated
and such
> It could even be on the prime issue tracker for prime proposals. Just
that it’s written down :)

Thanks Carter, but I understand Haskell Prime to be to assess mature/stable
proposals (preferably already delivered as extensions). This discussion is
at first going to be more exploratory:
* likes and dislikes about ScopedTypeVariables as currently.
* confusions experienced by users (especially newbies)
-- although absolute newbies wouldn't be using it(?), so intermediates?
* feedback from those teaching Haskell.
* wild ideas for possible alternative designs.
* possible improvements to the current design.
* I think we're all agreed that ScopedTypeVariables should have been in
Haskell from the beginning;
but it wasn't, so now we have to worry about backwards compatibility for
programs that worked around the omission.
Or do we? What code would break? How much pain would that cause?
* anything else?

> We have lots of forums, but your point is that certain sorts of
discussions never get going with the right audience – you especially point
to “confused beginners”.
> ... It’s quite a challenge because beginners tend not to be vocal, and
yet they are a crucial set of Haskell users. Every Haskell user started as
a beginner.

On this particular topic, there's plenty of confused people asking
questions on StackOverflow. (Heads up: they're especially asking why they
need explicit `forall` whereas in reguar Haskell that 'intermediates' see,
the forall is implicit.)

Can other people point me to questions/likes/dislikes on other forums?
Reddit for example.

If you've read this far, you now understand what we're trying to cover.
It's going to be random/varied thoughts at first, then perhaps coalescing
to an approach or two. At that point a formal proposal on github proper;
and the random stuff might be interesting background but will essentially
get archived/thrown away.

I do agree with David's suggestion that github Issue tracker looks like a
suitable solution. We can write formatted code and text. We can add links
and references. What do others think? Joachim has opened up Issues tracker,
as a try-out. If using it doesn't work out, that's fine and in keeping with
my "thrown away" above.

Also where else should I post links to this message to 'advertise' the
thread? I don't reddit much, so if that's suitable, please someone post

Thank you
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the Glasgow-haskell-users mailing list