From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
Subject: bug#21829: guix import hackage failures
Date: Thu, 26 Nov 2015 09:46:00 +0100
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	(Federico Beffa's message of "Thu, 26 Nov 2015 09:28:07 +0100")
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To: Federico Beffa <beffa@ieee.org>
Cc: 21829@debbugs.gnu.org

Federico Beffa <beffa@ieee.org> skribis:

> On Wed, Nov 25, 2015 at 10:45 PM, Ludovic Court=C3=A8s <ludo@gnu.org> wro=
te:
>> Federico Beffa <beffa@ieee.org> skribis:
>
> [...]
>
>>>>> +      ;; indentation based block recognition.
>>>>> +      (begin (unread-char #\newline port) (read-char port) 0)
>>>>
>>>> Isn=E2=80=99t this equivalent to: 0 ?
>>>
>>> No. This is because at the start of a new line we check if and how
>>> many indentation blocks have ended. If the last line doesn't terminate
>>> this check is no done.
>>
>> More generally, it looks like:
>>
>>   (begin (do-effect!) (undo-effect!) val)
>>
>> which I thought reduces to:
>>
>>   val
>
> Since we are doing IO, there are side effects. The key difference is
> the result of '(port-column port)' and that triggers what I mentioned.

Oooh, I see, thanks for explaining!  Then what about a comment like:

  Read a newline from PORT to reset its =E2=80=98port-column=E2=80=99, as e=
xpected by
  the indentation-based block recognition code.

I think it would be helpful for those like me who are hard of hearing.
;-)

Ludo=E2=80=99.