Stephan and Daniel, Thank you both very much. It worked! cheers, M ________________________________ From: Daniel Fischer To: Mohamed Sent: Tue, October 19, 2010 4:36:37 PM Subject: Re: [Haskell-beginners] small question Hi, On Tuesday 19 October 2010 16:13:05 you wrote:

Hello folks,

just a quickie here and would appreciate any help...

Stephen already told you that it should be if (honesty volunteer) ... , so

In this expression:

instance OBSERVATIONS Drinkability WaterWell Volunteer where observe (Drinkability waterWell) volunteer = volunteer {vReport = if (odorQuale (perceive (Odor waterWell) volunteer) == True && clarityQuale (perceive (Clarity waterWell) volunteer) == True && fullnessQuale (perceive (Fullness waterWell) volunteer) == True) then (if (honesty) then "drinkable" else "undrinkable") else (if (honesty) then "undrinkable" else "drinkable")}

Don't use 'if condition == True'. For Bool values, (== True) is the identity function, so 'condition == True' is exactly the same as 'condition'. Cheers, Daniel