Also worth adding that I kept most of Erlang’s syntax for data structures purposedly, so Erlang plays a big role on the syntax side of things too.
Yup, docstrings and doctests come from Python.
And the @derive feature in protocols is inspired by a similar feature in Haskell’s type classes.
I wouldn’t say Rake had a big influence on Mix. My experience with Bundler played a bigger role on Mix for sure.
If by lazy evaulation you mean streams, then citing Haskell is correct although I wouldn’t call it lazy evaluation. 
There was a lot of Haskell research involved for implementing streams in a purely functional fashion. The original idea came from Jessica Kerr’s talk on scalaz though. More info here: Introducing reducees « Plataformatec Blog
Not Clojure. It was from one of the ML variants (SML I think?) and F#.
