Chapter 4 Summary

  • patterns
    f [] = 0
    f (x:xs) = x + f xs
  • guards
    numword x 
    | x < 0     = "Negative"
    | x == 0    = "Zero"
    | otherwise = "Positive"
  • where
    h x = constant * x
       where constant = 100
  • let
    yis65 x = let (parabola = 10 * x * x + 25) in parabola == 65
  • case
    numit value = case (value) of 
        5 -> "Five"
        4 -> "Four"
        _ -> "Something else"