> Also I can't prove it, but I think a major source of pain in garbage collection is mutability, which is exacerbated by our fascination with object-oriented programming. I'd like to see a solid comparison of garbage collection overhead between functional and imperative languages.
I can only speak for Haskell's GC, but it's pretty conventional. You might think that GC is simpler for Haskell without mutability but you'd be wrong, because (1) Haskell actually gives you plenty of safe and unsafe ways to have mutability, safe ways such as the ST monad (not to be confused with the State monad), (2) laziness effectively is mutation: evaluating a value is effectively overwriting the closure to compute the value with the value itself. The lazy list is a pretty common sight in most Haskell code. So basically Haskell has a pretty conventional stop-the-world, generational GC not unlike imperative languages.
I can only speak for Haskell's GC, but it's pretty conventional. You might think that GC is simpler for Haskell without mutability but you'd be wrong, because (1) Haskell actually gives you plenty of safe and unsafe ways to have mutability, safe ways such as the ST monad (not to be confused with the State monad), (2) laziness effectively is mutation: evaluating a value is effectively overwriting the closure to compute the value with the value itself. The lazy list is a pretty common sight in most Haskell code. So basically Haskell has a pretty conventional stop-the-world, generational GC not unlike imperative languages.