] -> [a]
calcBmisFat xs = [ bmi | (w, h) <- xs, let bmi = w / h ^ 2, bmi > 25.0 ]

headCase :: [a] -> a
headCase xs = ca
calcBmisFat :: (RealFloat a) => [(a, a)] -> [a]
calcBmisFat xs = [ bmi | (w, h) <- xs, let bmi = w / h ^ 2, bmi > 25.0 ]
calcBmisFat xs = [ bmi | (w, h) <- xs, let bmi = w / h ^ 2, bmi > 25.0 ]