Re: [Haskell-cafe] using the writer monad to better understand foldl and foldr, and haskell debugging techniques in general

On Feb 11, 2008 7:53 AM, Felipe Lessa wrote:

read that IORef and do a big tell to the outside Writer monad. I'd say that this is a safe use of unsafePerformIO as it shouldn't break referential transparency. But without this hack I don't think we could

Well, not really as well. The IO action from unsafePerformIO may be executed several times, I guess. =) -- Felipe.