[Haskell-cafe] how do you debug programs?

Pepe Iborra mnislaih at gmail.com
Thu Sep 7 10:03:38 EDT 2006

On 07/09/2006, at 10:53, Tamas K Papp wrote:

> Dear Pepe,
> Thank you for the information.  I finally ended up working with
> Debug.Trace, and found the bug very quickly.  I also tried Hood, but
> couldn't load it in ghci: import Observe can't find the library, but
> % locate Observe
> /usr/lib/ghc-6.4.2/hslibs-imports/util/Observe.hi
> /usr/lib/ghc-6.4.2/hslibs-imports/util/Observe.p_hi
> /usr/lib/hugs/libraries/Hugs/Observe.hs
> /usr/lib/hugs/oldlib/Observe.hs
> Does importing from hslibs-imports require something special?

Hi Tamas

I'm glad to hear that you fixed it!

GHC includes Observe (the hs-libs-imports file you are seeing) only  
in the hidden 'util' package, which I believe is deprecated or not  
present in 6.6. If you want to use it, launch ghci with the flag '- 
package util'.
Or download Observe.hs from the Hood website and place it somewhere  
in the path.

Hmm, it would be handy to have a Cabal Hood package...


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