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Lab 6 — Practice with `for each` and lists

Skills: 3​

For all of these problems, first implement them with for each. Afterwards, see if there is a way to implement them with map or filter (without using any mutable variables). For some, it should be possible with just a single call to L.map or L.filter -- but for others in order to you it you may need to also use other functions like L.length.

  1. Design a function absolute-values that takes a list of numbers and returns a new list where each number has been converted to its absolute value (use num-abs).
  2. Design a function exactly-three-chars that takes a list of strings and returns a new list containing only the strings that have exactly 3 characters.
  3. Design a function all-even that takes a list of numbers and returns true if every number in the list is even, false otherwise.
  4. Design a function count-in-range that takes a list of numbers, a minimum value, and a maximum value, and returns how many numbers in the list are between the min and max (inclusive).