D1182: Implement improved error messages for ambiguous type variables (#10733)

Thomas Miedema thomasmiedema at gmail.com
Thu Sep 3 16:17:35 UTC 2015


The bug is trigger by Maybe now being a wired-in type. See
https://phabricator.haskell.org/D1208 for a workaround.

On Thu, Sep 3, 2015 at 6:13 PM, Edward Z. Yang <ezyang at mit.edu> wrote:

> It's certainly true that hsig is in flux, but it doesn't seem like
> injective type families should have broken this test.  I'll take a look.
>
> Edward
>
> Excerpts from Simon Peyton Jones's message of 2015-09-03 09:08:23 -0700:
> > Edward
> >
> > | Jan's injective type families commit is causing tcfail220 to fail, but
> > | that's unrelated to this ticket.
> >
> > This is true.  I told Jan to commit anyway because tcfail220 is a "hsig"
> test, and
> >  a) I know that hsigs are in flux (although I am not clear about how)
> >  b) I don't understand them enough to fix.
> >
> > So I hope it's ok to have broken this.  Jan and I can certainly help
> when you want to fix it.
> >
> > Meanwhile would you mark it as expect-broken.  (Although I am not sure
> that it's worth opening a fresh ticket for it.)
> >
> > thanks
> >
> > Simon
> >
> > | -----Original Message-----
> > | From: noreply at phabricator.haskell.org
> > | [mailto:noreply at phabricator.haskell.org]
> > | Sent: 03 September 2015 07:11
> > | To: Simon Peyton Jones
> > | Subject: [Differential] [Commented On] D1182: Implement improved error
> > | messages for ambiguous type variables (#10733)
> > |
> > | KaneTW added a comment.
> > |
> > | Jan's injective type families commit is causing tcfail220 to fail, but
> > | that's unrelated to this ticket.
> > |
> > |
> > | REPOSITORY
> > |   rGHC Glasgow Haskell Compiler
> > |
> > | REVISION DETAIL
> > |   https://phabricator.haskell.org/D1182
> > |
> > | EMAIL PREFERENCES
> > |   https://phabricator.haskell.org/settings/panel/emailpreferences/
> > |
> > | To: KaneTW, simonpj, bgamari, austin
> > | Cc: goldfire, simonpj, thomie
> --- End forwarded message ---
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