Backspace character in haskell-interactive-mode

[cmears]

QuickCheck uses backspace characters to make nice output while it is running tests. This does not work in haskell-interactive-mode:

λ> import Test.QuickCheck

λ> quickCheck (\xs -> reverse (reverse xs) == xs)
(0 tests)���������^H^H^H^H^H^H^H^H^H         ���������^H^H^H^H^H^H^H^H^H(1 test) [etc.]

I think the old inferior-haskell mode handles this properly, but I'm not sure how to fix it in the new interactive mode.

[chrisdone]

QuickCheck wrongly assumes it's in a terminal. I can add specific support for this in the REPL, but it's basically not a terminal.

[cmears]

I think it's fair to say that QuickCheck is wrong here. On a related note, should hIsTerminalDevice stdout return True in the REPL? (It currently does return True, but QuickCheck doesn't seem to check it in any case.)

[chrisdone]

It shouldn't really. I don't see any way in launching it in Elisp to not launch it as a terminal. One could pipe it to cat, but highly inportable.

[ShaneDrury]

I don't mean to dredge up a 4 year old issue, but it can be fixed by adding

(add-hook 'haskell-mode-hook
       '(lambda ()
          (setq process-connection-type nil)))

to your .emacs file. From https://sites.google.com/site/haskell/notes/ghci610emacsmadness

[ivan-m]

@ShaneDrury are you sure it's relevant? That page says it doesn't apply as of 6.10.3.