In Haskell with `head (sort list)` the entire list does not have to be sorted, depending on the sort implementation. Everything is lazy, so sort can sort the list just enough to return the smallest element.
Going beyond laziness, a compiler that can understand and exploit equations, could use `head (sort list) = smallest (list)` to make the program more efficient, going from O(n * log n) to O(n) complexity.