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Unable to install IHaskel kernel into Jupyter: "could not parse version number"

I've recently completed the installation instructions for Haskell, and have reached the final step where I run

ihaskell install

to install the IHaskell kernel into Jupyter. However at this point I'm stuck, with the error

Detected IPython, but could not parse version number.
ihaskell: 
Ran commands: 
which ipython
/usr/local/bin/ipython --version
which /usr/local/bin/ipython

Exception: ExitFailure 1

which makes no sense, since when I run those commands myself, I get a valid (and required) version number:

$ which ipython
/usr/local/bin/ipython

$ /usr/local/bin/ipython --version
4.0.0

$ which /usr/local/bin/ipython
/usr/local/bin/ipython

How do I proceed to install the IHaskell kernel into Jupyter?

Solution

  • This is a (soon to be addressed) limitation of the current version of IHaskell, which only supports IPhython 3.0.

    Stepping back to 3.0 with

    pip uninstall ipython
pip uninstall jupyter_core
pip install ipython[notebook]==3.0

    will resolve the problem until IHaskell is updated, at which point it will be safe to restore the current version of IPython with 

    pip install ipython[notebook] --upgrade

    Note that stepping back to 3.0 will result in view visible differences, though the expected location of settings files will change.