[Haskell-beginners] Data.Stream interleave implementation question

[Kim-Ee Yeoh]

On Wed, Feb 12, 2014 at 11:23 AM, Bryan Brady <bryan.brady at gmail.com> wrote:

> In the latter definition, Cons a (interleaveStreams bs as),
> (interleaveStreams bs as) is a thunk. The thunk should only be evaluated
> when it is needed.  In my original definition, (interleaveStreams as bs) is
> a thunk. The difference is an extra Cons (e.g., Cons b).  It seems like the
> additional Cons is causing problems, I just don't understand why. Can
> anyone point out what I'm missing?


As Isaac wrote, you want to look at the _left_ hand side, not the right.
It's pattern matching that impacts operational semantics.

-- Kim-Ee
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