I started my path with Programming Elixir and I have to say that the first chapters gave me a really good introduction to Recursion, Pattern Matching and the use of Tuples.
The Functional Programming Fundamentals lectures from Erik Meijer do a really good job of explaining the foundations of FP usually making direct comparisons between Haskell and C#.
My day to day work requires C# and I have been very happily adapting concepts learned from Elixir into it. I recently hit a wall on “how much more” could I exploit C# as a FP language and Functional Programming in C# has been revealing. To an extent it feels like “C# the Good Parts”.
While I have personally not delved into Racket, it seems like it would be the best point of entry regardless of your previous experience. 
Bought it this month, god only knows when I’ll get around to reading it…
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