>>> length [] 0 >>> length ['a', 'b', 'c'] 3 >>> length [1..] * Hangs forever *
>>> head [1, 2, 3] 1 >>> head [1..] 1 >>> head [] *** Exception: Prelude.head: empty listWARNING: This function is partial. You can use case-matching, uncons or listToMaybe instead.
>>> last [1, 2, 3] 3 >>> last [1..] * Hangs forever * >>> last [] *** Exception: Prelude.last: empty listWARNING: This function is partial. You can use reverse with case-matching, uncons or listToMaybe instead.
>>> last [1, 2, 3] 3 >>> last [1..] * Hangs forever * >>> last [] *** Exception: Prelude.last: empty list
>>> head [1, 2, 3] 1 >>> head [1..] 1 >>> head [] *** Exception: Prelude.head: empty list
>>> last [1, 2, 3] 3 >>> last [1..] * Hangs forever * >>> last [] Exception: Prelude.last: empty list
>>> head [1, 2, 3] 1 >>> head [1..] 1 >>> head [] Exception: Prelude.head: empty list
>>> mconcat ["Hello", " ", "Haskell", "!"] "Hello Haskell!"