I created a ticket and attached the files:

http://ghc.haskell.org/trac/ghc/ticket/8162

-- Akio



On Fri, Aug 23, 2013 at 7:46 PM, Simon Peyton-Jones <simonpj@microsoft.com> wrote:

Akio

 

Thanks that’s amazing!  I wonder if it’d be worth adding it, with commentary, (and attaching the files) as a Trac ticket?  I know its already fixed, but it’s great to be able to say “to see an example of why this is vital, see Trac #8324”, whereas email archives are more ephemeral somehow.

 

Simon

 

From: Glasgow-haskell-users [mailto:glasgow-haskell-users-bounces@haskell.org] On Behalf Of Akio Takano
Sent: 23 August 2013 11:35
To: glasgow-haskell-users@haskell.org; Richard Eisenberg
Subject: Fwd: New restrictions to open type families

 

(I forgot to send to the list, trying again)

Thank you very much for your detailed explanation!

 

On Fri, Aug 23, 2013 at 1:24 PM, Richard Eisenberg <eir@cis.upenn.edu> wrote:

This is a good question. Happily, there are at least two decent answers.

 

1) We're not sure that this problem cannot cause a segfault… it's just that we've been unable to produce one when trying. Perhaps we haven't tried hard enough.


I successfully constructed such an example.

https://github.com/takano-akio/type-family-overlap

- Akio