Since we're discussing particular courses. .. Can anyone recommend a good online course for learning about lambda calculus and type theory? I have some langua

Since we're discussing particular courses. .. Can anyone recommend a good online course for learning about lambda calculus and type theory? I have some language design ideas, but I suspect I'm at risk of various type system blunders until I understand those basics better. Edit: I really need it to be an online course, not just a text book. I find self-study to be particularly difficult for this topic.