What is some good introduction to lambda calculus? I have some background in set theory and automata and I am looking for a good place to start with lambda calculus.
 A: There is, of course, the very famous book by Barendregt, 


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*The Lambda Calculus, Its Syntax and Semantics (Studies in Logic and the Foundations of Mathematics, Volume 103). Revised Edition, North-Holland, 1985. (link to vendor)
which doesn't require much background except for the usual mathematical maturity. This is mostly about the untyped lambda calculus. He also has some introductory notes here. 
A: An introductory book that seems very nice to me is Lambda-Calculus and Combinators. An introduction by J. Roger Hindley and Jonathan P. Seldin.
A: The best books that I've found are:


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*Very basic: Hankin, An introduction to the lambda calculus for computer scientists.

*Advanced: Sorensen and Urzyczyn, Lectures on the Curry-Howard isomorphism.

*Advanced: Hindley, Basic simple type theory.

*The Bible: Barendregt, The lambda calculus: its syntax and semantics.

A: Another excellent book is "Lambda-calculus, types and models" Ellis Horwood (1993) by Jean-Louis Krivine http://www.pps.jussieu.fr/~krivine/articles/Lambda.pdf
A: Stoy's book:
Joseph E. Stoy, Denotational Semantics: The Scott-Strachey Approach to Programming Language Semantics. MIT Press, Cambridge, Massachusetts, 1977
Is a classic, and highly recommended.
A: I really enjoy Types and Programming Languages by Benjamin C. Pierce. We used this for a course on the lambda calculus, and I felt this was a great way for a mathematician to learn the subject
A: Proof and Types is a good place to learn about the Curry-Howard isomorphism. 
