On 13/11/06, Valentin Gjorgjioski <[EMAIL PROTECTED]> wrote:
I'm pretty new in Haskell, few days since I started learning it. I want
to debu my programs. I'm currently using WinHugs, and I prefer debugger
for this.
I tried googling and I found Hugs.Observer.
I like it how it works, but still I have one BIG problem with it. It
doesn't work well with floats.
Following example
import Hugs.Observe
ex8 :: [Float]
ex8 = (observe "after reverse" ) reverse [10.0,7.0,3.0,0.0,4.0]
gives me
>ex8
[4.0,0.0,3.0,7.0,10.0]
>>>>>>> Observations <<<<<<
after reverse
{ \ ($-990871 : $-990888 : $-990905 : $-990922 : $-990939 : []) ->
$-990939 : $-990922 : $-990905 : $-990888 : $-990871 : []
}
First of all, I don't get this behaviour in Hugs 20050308 on Ubuntu.
Main> ex8
[4.0,0.0,3.0,7.0,10.0]
Observations <<<<<<
after reverse
{ \ (10.0 : 7.0 : 3.0 : 0.0 : 4.0 : []) -> 4.0 : 0.0 : 3.0 : 7.0 : 10.0 : []
}
and:
Main> ex8 `seq` ()
()
Observations <<<<<<
after reverse
{ \ (_ : _ : _ : _ : _ : []) -> _ : _
}
So it might just be the version which you have.
I think that the $<n> values are perhaps representations of
unevaluated thunks. Try it with a string, or something like ex =
(observe "after replicate") (replicate 3) (5+5) and see what you get
(should be a list with 3 elements that are all the same thunk). Also
try:
ex8 = foldr seq () xs `seq` (observe "after reverse" ) reverse xs
where xs = [10.0,7.0,3.0,0.0,4.0]
to see if forcing the values in the list first causes any change in the output.
- Cale
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