[Haskell-beginners] Important coding guideline and library proposal

Guideline: NEVER, *never ever*, use 'length' ***unless you really want to know the exact length of a list*** Proposal: rename 'length' to 'yesIReallyWantToKnowTheExactLengthOfThisListSoPleaseCalculateItForMe' to reduce performance bugs caused by naive uses of length.