Infrequently I've seen the word "combinator" in Lisp/Scheme books or video lectures. But it just appears like a glint and I never pay attention to. However, while studying lambda calculus I found out that wikipedia says
"[combinatory logic] has more recently been used in computer science as a theoretical model of computation and also as a basis for the design of functional programming languages."
I would like to spend some time on it. Would you please recommend some good readings?
The first book that comes to my mind is Raymond Smullyan's To Mock a Mockingbird. It's a puzzle book, like most of Smullyan's, but the puzzles in it are very relevant to functional programming and combinatory logic.
I'd recommend Jonathan Seldin's book chapter "The Logic of Church and Curry". Seldin has done a lot to bring the work of Curry and Hindley to the masses. If you have access to a university library, you can also go straight to the source: Haskell B. Curry's two-volume work entitled Combinatory Logic. But Seldin will be a more accessible introduction.