Re: problem with echo prompting in ghci (visible in emacs)

2008/11/16 Conal Elliott :

I'm still looking for a solution to this problem. I've heard from a few people who are affected also, but not any solution.

Barring a solution to ghci's behavior, does someone have an emacs-based workaround?

- Conal

On Tue, Nov 11, 2008 at 4:41 PM, Conal Elliott wrote:

...

ghci echoes all of my input in emacs, when run via haskell-mode or via "M-x shell", which then confuses various useful haskell-mode features. I built it from sources. At the time I didn't have libedit-dev, so today I installed libedit-dev (version 2.11~20080614 on ubuntu), did a clean make & install, and I get exactly the same behavior.

Does anyone have experience in getting through this problem? Willing to help me out?

Thanks,

- Conal

Hi Conal, The problem is that eshell tells subprocesses that they're running in a terminal (e.g., when queried via hIsTerminalDevice), but always echos user input itself regardless of the tty's ECHO attribute. This confuses libedit, which assumes that if it's connected to a terminal then it can turn off echoing in order to run its own rich line editor. In "M-x shell", you can work around this issue by starting ghci with, for example, "cat | ghci" to prevent ghci and libedit from trying to run as if in a terminal. Probably something similar could be done for haskell-mode; I'm not familiar enough with emacs to fix it myself. Incidentally, googling revealed that zsh has a similar issue: http://www.zsh.org/mla/users/2001/msg00014.html (section 3.10) Hope that helps, -Judah