"How does functional programming in multi-paradigm languages (e.g. Java, Python) compare to purely functional languages?"
Mr Dawkins
- Haskell: the Craft of Functional Programming - Simon Thompson
- Java 8 Lambdas: A Peek Under the Hood - InfoQ
- Java 8: Lambdas - Oracle
- Why Python is slow: Looking Under the Hood - Jake Vanderplas
- ...and a lot of source code.