For most systems, the default return type is "Expression":

Delete the session objects:

Numbers, strings, lists and associations are automatically imported for the "Expression" return type:

Delete the session objects:

The return type of "String" returns a string of the result in the external language:

Delete the session objects:

When using a database, the default return type is "Dataset":

"ReturnType" can be used to return data in a different form:

Delete the session objects:

Evaluate code using a specified "Evaluator":

Delete the session objects:

An Association can be used to start a Python provisioned environment:

Use the session to evaluate the code:

Delete the session objects:

When using a File with the "SQL" evaluator, the target can be a path to an SQLite file or a DatabaseReference specification:

Delete the session objects:

Register an evaluator using a name:

Start a session using the registered evaluator by referring to it by name:

Use the session:

Close the session:

Start an evaluator with a given "ID":

The operation is idempotent; starting a session with the same "ID" will return the same running session:

You can check that there is only one running session, even if you run StartExternalSession two times:

Close the session:

Use "SessionProlog" to perform a side effect at the start of a session:

Delete the session objects:

Start an external session and import a library at the beginning of the session:

Evaluate a function from the imported library:

Delete the session object:

Use "SessionEpilog" to perform a side effect at the end of a session:

Delete the session object:

Use "Prolog" to perform a side effect before every evaluation:

Delete the session object:

Use "Epilog" to perform a side effect after every evaluation:

Delete the session object: