On 11/09/18 17:11, yary wrote: > "Nil... it's a constant, so you have to use =:= to check for equality." > > Can you elaborate on that requirement? == works for an equality checks > with numeric constants- must be more than Nil's constant-ness that > makes one use =:= - perhaps that Nil doesn't numify to anything?
Nil does numify, but using == comparison for this is still problematic for two reasons: 1) Nil numifies to 0, which is a valid "true" result for the index method and 2) it outputs a warning: Use of Nil in numeric context in block <unit> at -e line 1 using ~~ instead of =:= should also be okay, or checking for definedness with either .defined or using "with" instead of "if", which is very useful especially for index and friends. HTH - Timo
