On 13/11/06, Valentin Gjorgjioski
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