> Python is the de facto glue language with one of the biggest ecosystems out there
I never contested that.
> ML is very specifically about manipulating data (a fundamentally dynamic task)
I disagree strongly with using dynamic languages for data. Data has dimensions, units, types. You need to know that you're not adding coats to horses or USD to EUR. You need to know that you didn't silently sliced by the wrong axis.
You may want formal verifications. You may to transform data without worrying about silent errors.
All the "metadata" and wrapper classes ML in Python are just trying to give you what the language can't.
> a very glue-task. Give me any language better than python for that
That's my point exactly. ML has evolved beyond glueing a few C libraries. It needs complex, big programs, which is an area where Python is terrible. Also the different nature of the "glued" components (each with its own data formats, protocols and calling conventions) makes the glue a mish-mash of untyped mixed magic idioms.