This is a good introduction to the concept of diglossia in the Sinhala language.
https://www.jstor.org/stable/30029181
Here is the definition of a diglossia he cites and feels it applies for the most part to Sinhala:
It has a soft paywall you can get around by simply registering for the site.
I share it here because I think some of our language learning members would find it interesting, especially in regards to Sanskrit and Pali loan words. One new interesting tidbit I picked up is that Sinhala tends to not borrow verbs from Sanskrit, despite heavy use of Sanskrit nouns. Curious!
