Why I can not highlight Scala functions?

[Norlandz]

I have 2 pieces of code, one in Python, one in Scala, in Browser.
They are highlighted, but not good enough.

Q.1
I dont understand why the functions of Python / Scala are not highlighted.
(Though, if I use Java / C they are highlighted.)

Q.2
Im trying to highlight the functions in those Code.

So I did the following:

  const obj_CodeSyntaxHighlight_general_extra = {
    'function': {
      pattern: /\w+(?=\()/,
    },
  }

  Object.assign(Prism.languages.python, obj_CodeSyntaxHighlight_general_extra);
  Object.assign(Prism.languages.scala, obj_CodeSyntaxHighlight_general_extra);

  Prism.highlightAll();

And this is the result:

Python:

Scala:

As you can see,
the code in Python can have functions highlighted as expected.
the code in Scala can NOT have functions highlighted as expected.
Why?

(
note, I also tried the following regex pattern for Scala, just for testing
pattern: /where/ - work
pattern: /\w+/, - work
pattern: /\w+\(/, - not work
)

[Norlandz]

I dont have deep knowledge with PrismJs.
But I check the source code again today.

And found the following:

delete Prism.languages.scala['class-name'];
delete Prism.languages.scala['function'];
delete Prism.languages.scala['constant'];

I commented out these lines, and the Scala function code syntax highlight works.

Dont know why these lines are there.