On 06/lug/09, at 14:19, Roberto Ostinelli wrote: > foo(..) when (islist(X) == true ansalso (lists:nth(1,X) == 'test') - > > .. that would be foo(..) when (islist(X) =:= true) ansalso (lists:nth(1,X) =:= 'test') - > .. pardon me i was in python mode. r.