Notebook hangs on any cell execution about ihaskell

[gibiansky]

If your cell stays marked as busy, the kernel is almost certainly dead. The console interface is a bit broken right now - I've been developing mostly for notebook and really need to work on the console as well. :{ code :} is not supported, either; sorry about that... feel free to create a feature request issue.

As for notebook errors - can you switch back to 03c5a95, run IHaskell setup and IHaskell notebook and then find a minimal broken example? Then, paste output of those two commands as well as the files in ~/.ipython/profile_haskell/*.py.

Although everything should work on IPython 1.0.0, you could also try switching to HEAD and seeing if it works. I'm not sure why the kernel is dying and need a bit more info to go on :(

[wcbeard]

:{ code :} is not supported

Really? I paste this into the console and it seems to work:

In [3]: :{
   ...: data Value = X Int
   ...:            | Y String
   ...:            | Z Float
   ...:            deriving Show
   ...:
   ...: let values = [X 20,
   ...:               Y "Test",
   ...:               Z 0.5]
   ...: mapM_ print values
   ...: :}
Out[3]:
X 20
Y "Test"
Z 0.5

I may have been unclear, but I only tried this in the console, and it works with or without :{ :}. I'm new to Haskell, but I thought I read that it's required for multiline ghci input. But I assumed multiline input is expected in the notebook without :{ :} by default, so it would be unnecessary anyways.

[wcbeard]

After

git stash
git checkout 03c5a95
IHaskell setup
cabal install
IHaskell notebook

I tried to print again, and terminal output is here. I'll update IPython in a minute and see if that helps.

[gibiansky]

Whoa, you're right! About the :{ ... :}. ...I think this might be an accident. Python recognizes the ':' characters as Python delimiters and thus enters multiline mode. Then, IHaskell interprets :{ and :} as directives (along the lines of :t). It doesn't report an error (that's a bug!) and just does nothing. Then, it interprets the rest of the code block as it would for the notebook. As a result, :{ and :} work... by accident. Whoa.

[wcbeard]

Interesting on multilines...didn't know python sees ':' as a delimiter, maybe an IPython thing? I think they have really flexible parsing, you can even paste in In [1]: ... or >>> in the cells at the start of a line and it doesn't care. (Makes it really nice for copy/pasting stuff from the web.)

[gibiansky]

By 'delimiter', I mean that ':' denotes the beginning of an indented block, as in

if condition:
    # Indented block
    pass

IPython handles that by starting a multiline input, which helps us in this case!

[wcbeard]

I just upgraded ipython--it was at 1.0.0 (4481c323e0d), now at 1.1.0 (7c2ea3a) (or did you mean I should try the 2.0 version?). cabal install'd and IHaskell setup'd again, and I'm still getting a busy signal. Though output looks similar. Not terribly descriptive...any other ideas on how to get logged info that could be useful?

[wcbeard]

I had been hesitant about upgrading to v2.0 dev since it wouldn't work for either language. Figured out the browser cache was messing things up so I cleared it and have the notebook working on both languages. Not sure if it was the ipython version or cache, but it's working! Thanks!

And for anyone else out there having trouble w/ IPython notebook dev version... clear your cache!

[gibiansky]

Huh, that's very strange. How do you clear the IPython cache? I'd like to add that to the README as a troubleshooting tip.

[wcbeard]

It's just the browser cache for whatever browser you're in. F5 usually works, but I had to go Settings > Show advanced > Clear browsing data > empty the cache in Chrome.

Also, I switched back to IP 1.1.0, and it didn't work, so that probably had more to do with it than the cache, but clearing the cache would be necessary for the IP version upgrade, I think. I've got a virtualenv working for IHaskell using IP 2.0 now, so both languages are happy for the time being...