Perhaps x is evaluated earlier than you think, i.e. before the trace (due to some strictness analysis?). But this is a just a guess. I usually use trace outermost in my expression, not within a let. I never had a problem with it: fA :: SomeInput -> SomeResult fA a = trace ("Entering fA") $ f a -- or even: fA a = trace ("Entering fA") $ f a HTH Thomas Am 14.05.2013 15:03, schrieb hanjoosten:
My project is split in two packages, A and B, where B uses A. All together, there are about 100 haskell modules. Currently, there seems to be a loop somewere, that only seems to occur when working with rather large datastructures. I use trace (from Debug.Trace) to see what exactly is going on. As long as I trace functions from B, trace works as expected. However, at some point I need to trace into functions supplied by package A.
In package A I have a function like this: (I have simplified the function)
fA :: SomeInput -> SomeResult fA a = let x = f a in trace ("Entering fA") x
(The function f is defined in package A)
In package B, I have a function like this:
fB :: SomeInput -> SomeResult fB a = let x = fA a in trace ( "Entering fB") x
At runtime, I get the message Entering fB
and then nothing more. a lot of cpu is used, but no more output.
I have made some wrappers like the ones above. As long as they are in the same package, trace works fine. However, when entering a function from the other package, there is no more debug output.
This is very anoying. Anyone some suggestions? Is this a bug?
I use the haskell platform 12.4.0.0 on a windows 7 machine.
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