lists.md

Introduction

Use the following guidelines to manipulate lists.

1. The output list is initially empty or some fixed sequence.
2. Use for x in xs: to process each element of the input sequence xs in turn.
3. Process the element x appropriately.
4. Append the element corresponding to x into the output list.
5. Once you've finished processing all elements, return the output list.

Questions

1. Write a function length that takes a list and returns its length.
2. Write a function max that takes a list and returns the largest number in the list.
3. Write a function first_negative that takes a list and returns the first negative number in the list. If all numbers are non-negative, return 0.