Your message dated Thu, 1 Dec 2016 18:13:43 +0200
with message-id <20161201161343.drrjrqdyddt5m...@gmail.com>
and subject line Re: Bug#846279: ghc: Problems with Backspace, Delete and arrow 
keys
has caused the Debian Bug report #846279,
regarding ghc: Problems with Backspace, Delete and arrow keys
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact ow...@bugs.debian.org
immediately.)


-- 
846279: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=846279
Debian Bug Tracking System
Contact ow...@bugs.debian.org with problems
--- Begin Message ---
Package: ghc
Version: 8.0.1-14
Severity: normal

Dear Maintainer,

Since upgrading to ghc 8.0.1, when trying to backspace user-entered text (e.g. 
a getLine event) in a
running haskell program (whether compiled with this version of ghc, or 
interpreted), the terminal
displays "^?" for backspace, "^[[3~" for delete and other codes for arrow keys.

It appears to be previously reported, and resolved, here: 
https://ghc.haskell.org/trac/ghc/ticket/2606

Looks to be a problem with how ghci is compiled and 
libedit/libreadline/ncurses-dev as the module 
"System.Console.Editline.Readline" is missing:

GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
Prelude> :browse System.Console.Editline.Readline

<no location info>: error:
    Could not find module ‘System.Console.Editline.Readline’
    It is not a module in the current program, or in any known package.


Many thanks!

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.8.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages ghc depends on:
ii  dpkg             1.18.15
ii  gcc              4:6.1.1-1
ii  libbsd-dev       0.8.3-1
ii  libc6            2.24-5
ii  libc6-dev        2.24-5
ii  libffi-dev       3.2.1-6
ii  libffi6          3.2.1-6
ii  libgmp-dev       2:6.1.1+dfsg-1
ii  libgmp10         2:6.1.1+dfsg-1
ii  libncurses5-dev  6.0+20160917-1
ii  libtinfo5        6.0+20160917-1

ghc recommends no packages.

Versions of packages ghc suggests:
pn  ghc-doc      <none>
pn  ghc-prof     <none>
pn  haskell-doc  <none>
pn  llvm-3.7     <none>
ii  perl         5.24.1~rc3-3

-- no debconf information

--- End Message ---
--- Begin Message ---
On Thu, Dec 01, 2016 at 04:22PM, Richard Smith wrote:
> Thanks for your further assistance. Upon further investigation, I
> think I've found that this happens if I use...
> 
> hSetBuffering stdout NoBuffering
> hSetBuffering stdin NoBuffering
> 
> ...at the very start of my main statement, so it might indeed be the
> correct behaviour, although I've not had this happen before. 

I believe this is the correct behavior. I also tried disabling
buffering and the results are the same for both v7.10.3 and v8.0.1
(i.e., backspace is not working) which means there is no regression.

> Curiously, I also get the same behaviour in ghci when not using hSetBuffering 
> at all.

That is also the correct behavior. It has always been like this (as an
example, see the following question on stackoverflow, which is from 2014): 

  
http://stackoverflow.com/questions/21114222/difference-in-getline-functionality-with-ghci-vs-runhaskell
 
> What do you think? Have I made a mistake with this bug report?

I for sure learned something from this bug report, so I don't consider
this a mistake ;-)

I am closing this bug report, since this seems to be the intended behavior.

Best,

-- 
Ilias

--- End Message ---

Reply via email to