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Re: [Coq-Club] [Type Classes]: avoid duplication of instances


chronological Thread 
  • From: St�phane Lescuyer <stephane.lescuyer AT polytechnique.org>
  • To: Aaron Bohannon <bohannon AT cis.upenn.edu>
  • Cc: Alexandre Pilkiewicz <alexandre.pilkiewicz AT polytechnique.org>, Coq Club <coq-club AT inria.fr>
  • Subject: Re: [Coq-Club] [Type Classes]: avoid duplication of instances
  • Date: Wed, 13 Oct 2010 21:17:58 +0200
  • Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=XNkuv1WBlFInzq+HEyjQyU4XGtqDrlPZu2r2yz9DMH/umQ6Z9MUQ1gn/5/knFyc4IT rC6zwt4yNSQvS8iYBPS44yiFkJBT184WmJCIKGaWrd4p1WBDIb1SFhCmYCxtvN5uX+f0 1rzeBFCrY9Q7MggDhr6+Fmsb6+RLrpnLbAdGM=

Don't worry, it's just Bug #2222 :-) it has been corrected last week
only, so it was still there in the release candidate. The trunk
version of branch 8.3 should be ok.

Stéphane

2010/10/13 Aaron Bohannon 
<bohannon AT cis.upenn.edu>:
> 2010/10/12 Stéphane Lescuyer 
> <stephane.lescuyer AT polytechnique.org>:
>>  1 subgoal
>>  A : Type
>>  EqA : EqDec A
>>  x : A
>>  y : A
>>  H : equal x y = true
>> ======================
>>  x = y
>>> destruct (eq_dec x y).
>
> Hi Stéphane,
>
> I am rather disappointed to find out that this only works in this way
> in Coq 8.2.  In Coq 8.3rc1, to achieve the same effect, you must write
>
> destruct (@eq_dec A EqA x y).
>
> While this doesn't entirely negate the usefulness of this technique, I
> really wish it was as easy in 8.3 as 8.2.  What happened?  Is there
> some new vernacular command I have to use to get 8.3 to cooperate?
>
>  - Aaron
>



-- 
I'm the kind of guy that until it happens, I won't worry about it. -
R.H. RoY05, MVP06




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