That page is incorrect about GHC's memory management -- I verified this with a question to haskell-cafe around 2014, and I guess no one got around to updating i

That page is incorrect about GHC's memory management -- I verified this with a question to haskell-cafe around 2014, and I guess no one got around to updating it. The linked paper at the bottom of the article explains how things work and have worked for a long time now. The source of cyclic references, and even references from old to new generations, comes from "thunks" (unevaluated lazy computations). Haskell guarantees that a thunk only ever gets evaluated once, and the way this is implemented is that the thunk is mutated with a pointer to the evaluation result. So the garbage collector needs to deal with mutations, cyclic references, and references from old to new generations. (All that in a language with supposedly immutable data!)