I think the official book is already quite good, and you can participate.
(...I was also thinking of contributing some of the bits I learned in this topic to the book, but maybe this is more for someone who knows more about the Swift internals and the intentions. In my last comment I speculated about reference counting — which I think is a very good thing — hindering an “isolation mechanism” akin to Java-like exceptions, but honestly I do not know enough about these issues to be in the positions to inform other people about it.)
Well, I know Haskell and today I am very much opposed to its strict functional idioms. This is a bit another topic than safeness, to my knowledge the addition of two numbers in Haskell overflows silently as in Java. And Haskell suffers a lot from unexpected changes in efficiency when changing the code, that gives you another kind of unsafeness; from what I have read the Swift people work very hard to avoid those traps. What is interesting about Haskell are its variants with dependent types.