After a a println command "Ok" is printed instead of the actual string to be printed.

[oroszgy]

Having the row

println("hello")

Ok is printed and not "Hello"

[happy15]

+1

[apatrida]

The result of println(...) is of type Unit and therefore on that type of response the Ok is printed as a result of the call. If you want to print "Hello" you can just put that string. or for example of a variable:

>>> val x = 10;
Ok

>>> x
10

Do other interpreters copy the output of stdout to the response?

[apatrida]

So for something that returns Unit type, we can print <no return value> instead to make it clearer, ... I'm asking about capturing standard-out from the reply eval engine now, if so we can fix capturing stdout output as well.

[oroszgy]

Hi, thanks for the reply. Other interpreters tend to capture the stdout, so I think that would be a useful feature here as well.

[apatrida]

I did a quick hack to check capturing stdout, and I was able to do so. But, it isn't pretty. Need to see if the evaluator can have it set directly instead of changing the global System.out printstream.

[apatrida]

Ok, basically just forking the System.out both to the console and to the publishing of output back to Jupyter. Anything running that does output will accidentally send data back to Jupyter, so inadvertant output could come back. And not sure if Jupyter limits how much it accepts so that it doesn't end up with megs of data coming back on some accident. I think a configuration parameter would be good for turning the forking of stdout on, and also the limit per eval call that could be sent back as a fail-safe.

[apatrida]

I have some refactoring to do, then will commit fixes for this and the repeat crash later...

[apatrida]

When piping stdout back, it shows up in jupyter-console, but in jupyter-notebook it does not. So therefore stdout has to be mapped back as the return value. I'll take a look to see what other kernels do in the same situation (if they pass back something with a mime type, or just as a text value, ...)

[apatrida]

If you want, please try my fork at https://github.com/apatrida/kotlin-jupyter

and I'll do a PR from there based on feedback.

[apatrida]

[apatrida]

What does not work is if you do output AND return a value, the value will win.

[apatrida]

@ligee please close, fixed in previous PR