Basic Examples (3) 

Create an external session and set it as the default for "ExternalLanguage" cells:

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Set a value in the session:

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Check that the "ExternalLanguage" cell uses the same session:

x

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Reading and writing values works bidirectionally:

x = 2.71828

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Start a new session for the "ExternalLanguage" cell with a specific python executable:

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Now the python external language cell session will have the specified environment:

import numpy x = numpy.ones([10,10])

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Bind an existing session object to the "ExternalLanguage" cell:

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Verify the external language cell is running the same session:

x

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Options (3) 

Remove prior external sessions and start anew:

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Now there is a single session:

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Verify with the external language cell:

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The "Language" option may be set to any properly configured external evaluation system:

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Verify the external language cell is running the newly created Julia session:

x = sqrt(144)

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Change the executable of the "Shell" session:

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Now it uses ZSH instead of BASH:

echo $0

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You can export an environmental variable in the session:

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And verify that the "Shell" external cell uses that same session:

echo $VAL

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Applications (3) 

When you have one or more different sessions, you can explicitly access them individually with ExternalEvaluate:

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However, "ExternalLanguge" cells are much more convenient for multiline code, but simply creating such a cell (shift + >) will start a new and inaccessible session:

name

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Using SetLanguageCellSession allows you toggle between them:

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name

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