[Haskell-cafe] Laziness leaks
oddron at gmail.com
Tue Jun 3 17:14:30 EDT 2008
I was looking at the real time queues in  and I wanted to see what
would happen if I tried to write one in Haskell. The easy part was
translating the real time queue from , p43 into Haskell.
The hard part is testing to see if the rotations really happen what
they should. Basically, I decided to use Debug.Trace.trace to see
when rotations were actually occurring.
I pushed the numbers 1 to 10 into the queue, and then I popped the
queue ten times. What I found is that none of the rotations would
actually take place until the first time I actually tried to /display
the value/ of a popped element. What I realized is that my test
driver is lazy. I figured out that I could put a bunch of 'seq'
functions in the test driver to get the rotations to happen.
My demonstration code is in:
This leads to two questions:
1. If I find a laziness leak, is 'seq' the appropriate way to plug it?
2. Is there any way to systematically search for or detect laziness
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