Haskell Cookbook

Operations on a list

Once we have a list, we can do various operations, such as the following ones:

• init :: [a] -> [a]: Take all but the last element of the list. This is shown in snippet 8.
• take :: Int -> [a] -> [a]: Take, at the most, the first n elements of the list (shown as the Int argument). If the list has less than n elements, then it will consume the entire list. This is shown in snippet 9.

  In snippet 9, we worked on an infinite list and took only the first 10 elements. This works in Haskell, because in Haskell, nothing is evaluated until computation needs a value. Hence, even if we have an infinite list, when we take the first 10 elements, only 10 elements of the list are evaluated. Such things are not possible in strict languages. ...