[Haskell-beginners] Fwd: Stuck in debug of loop detection

[Lev Broido]

---------- Forwarded message ----------
From: Lev Broido <lev.broido at gmail.com>
Date: Mon, Oct 31, 2011 at 2:31 PM
Subject: Stuck in debug of loop detection
To: beginners at haskell.org, haskell-cafe at haskell.org


Hi
I am playing around with building graph using 'tying the knote' technique ,
according to rule a is child of b iff predicate a b == true
Additional step is to detect loops in graph to enable it's print . Then I
am using graph traversal to detect loops prior to calling show .

For now I am stuck debugging loop detection . I am using 'trace' for a
first time and I am not sure I am fully understanding it's behavior
In additional I tried to make all calculations strict for debug .

Can you please provide tips / review code .

My code is at
http://pastebin.com/5RvQ42z2

Thanks,
Lev
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