Hello, I'm trying to program an implementation of the St. Petersburg game in Haskell. There is a coin toss implied, and the random-number generation is driving me quite mad. So far, I've tried this: import Random increment :: Int -> Int increment b = b + 1 main = do let b = 0 let c = randomRIO (1,2) until (c == 1) increment b return b This is intended to print the number of consecutive heads (i.e., 2) before the first tail, but I get the following error: ERROR "StPetersburg.hs":8 - Type error in application *** Expression : until (c == 1) increment b *** Term : c == 1 *** Type : Bool *** Does not match : Int -> Bool I don't really see what's going on, so any help will be more than welcome. I hope this is a suitable question for the Haskell Café list. I'm using Hugs in an Ubuntu box, in case that should be useful. Thanks, Manolo