3. Functions in Depth

Activity 3.01: Building a Distance and Cost Calculator

Solution:

1. Start by defining the walking-speed and driving-speed constants:

    (def walking-speed 4)
   (def driving-speed 70)

2. Create two other constants representing two locations with the coordinates :lat and :lon. You can use the previous example with Paris and Bordeaux or look up your own. You will be using them to test your distance and itinerary functions:

    (def paris {:lat 48.856483 :lon 2.352413})
   (def bordeaux {:lat 44.834999  :lon -0.575490})

3. Create the distance function. It should take two parameters representing the two locations for which we need to calculate the distance. You can use a combination of sequential and associative destructuring right in the function parameters to disassemble the latitude and longitude from both locations. You can decompose the steps of the calculation in a let expression and use the Math/cos function to calculate the cosine and Math/sqrt to calculate...