Chapter 3 Walkthrough

Cubes

• List: all perfect cubes divisible by 16 and less than N.
• Write signature.

cubes 100 == [64]
cubes 600 == [64, 512]

Partial Average

• Average first N items of a list.
• Write signature.

partAvg 3 [10,15,50,10000] == 25

Say GPA

• Make a string “My GPA is 3.10”.
• Number is parameter.
• Write signature.

sayGPA 3.10 == "My GPA is 3.10"

Count Up I

• Given start and end numbers, print a string.
• Usage: countUp 3 7
• Result: “I can count from 3 to 7: [3, 4, 5, 6, 7]”

countUp 3 7 == "I can count from 3 to 7: [3, 4, 5, 6, 7]"

Count Up II

• Given strings containing start and end numbers, as if typed.
• Same as Count Up I.

countUpII "3" "7" == "I can count from 3 to 7: [3, 4, 5, 6, 7]"

Need read?

Use type signatures and helper functions.

Sample Standard Deviation

Input a list of numbers, say there are n of them.

1. Find the average (called “xbar”).
2. Find the sum of (x-xbar)^2 for each x in the list.
3. Divide by n-1.
4. Take the square root.