[Haskell-beginners] Data.Stream interleave implementation question

[Curt McDowell]

Funny, I was trying the same Homework, implemented interleaveStreams using 
the same algorithm you did (taking one item from each stream per recursive 
call), and got the same result with the ruler function hanging. It was also 
fixed by changing interleaveStreams to take from just one stream per call 
and switch back and forth between streams.

This happened even though I implemented my ruler function itself 
recursively:

ruler' :: Integer -> Stream Integer
ruler' n = interleaveStreams (streamRepeat n) (ruler' (n + 1))

ruler = ruler' 0

Sorry, but I also don't know why. I speculate that if one were to expand it 
out on pencil and paper, they'd find that the interleaved stream somehow 
expands at a different rate than the ruler (half or twice).

-Curt