Hi all, I kind of stumbled into this while doing something else - but I thought it was worth posting since I have never actually managed to crash ghci before :) Prelude> let d = [1..1000000000000] :: [Int] Prelude> sum d 0 0? I mean, I might have expected an integer overflow, but 0? And now the really odd part... take away one zero Prelude> let d = [1..100000000000] :: [Int] Prelude> sum d < ghci crashes and quits > A slightly more reasonable number.. Prelude> let d = [1..10000000] :: [Int] Prelude> sum d *** Exception: stack overflow At least I can appreciate what is going on in this one :) I'm aware that this is a silly way to sum from 1 to n, but I am at a loss to explain the above behavior (Except the stack overflow, that is fair enough). I'm also aware that Int is a machine Int, not a clever infinite haskell Int. Any ideas? All the best, Phil