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Exercises: Using built-in data#Try

1. Try calling some the built-in operations like <=, =, and, or, not, equal? on various data values, e.g., is 17 times 18 bigger than 256?

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1. What are the contracts of these built-in functions?
   *Choose any two, and write down the contract.
   *Verify your guess by asking the labby
   or by using DrScheme's Help Desk to look at the
   manual for the Beginning Student language.
   *Practice writing a function which returns a Boolean:
   Following the design recipe,
   write

   Code Block
   within-two?

   which takes in two numbers
   m and n, and returns true if
   m - n and {{ n - m}} are both
   less than 2.
   Otherwise, it should return false.
   (For learning purposes only, don't use

   Code Block
   abs

   ,
   which computes the absolute value. Also, don't use
   

   Code Block
   cond

   or

   Code Block
   if

   .)
   Your examples can look like

   Code Block
   (boolean=? (within-two? 99.8 101) true) (boolean=? (within-two? 5 -5) false)

Sample solution

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Other Basics

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