Scripting Languages G22.3033-002 Summer 2008

• quiz1: Quiz 1.

Scripting Languages G22.3033-002 Summer 2008 quiz1

Thursday 6/5/2008. 30 points.

http://www.cs.nyu.edu/courses/summer08/G22.3033-002/

• quiz1-problems: Quiz 1 problems.

Quiz 1 problems.

• quiz1-1: quiz1-1 Gradual typing
• quiz1-2: quiz1-2 Precedence and associativity
• quiz1-3: quiz1-3 Call-backs

quiz1-1 Gradual typing

(10 points) Add explicit type annotations to the following VBA module.

     Function geometricMean(arr())
       geometricMean = 1
       For i = LBound(arr) To UBound(arr)
         geometricMean = geometricMean * arr(i)
       Next i
       n = 1 + UBound(arr) - LBound(arr)
       geometricMean = geometricMean ^ (1.0 / n)
     End Function
     Sub main()
       Dim A(1)
       A(0) = 1: A(1) = 2
       Debug.Print geometricMean(A)
     End Sub

quiz1-2 Precedence and associativity

(10 points) Consider the following excerpt of Perl's operator table.

     Operator  Arity  Associativity  Description
     **        2      right          exponentiation
     *         2      left           multiplication
     =         2      right          assignment

Fully parenthesize the following expression: $x = $y = 3 ** 3 ** 3 * 2.

quiz1-3 Call-backs

(4+3+3 = 10 points)

1. How are call-backs supported in VBA user forms?
2. Give an advantage for this language design choice.
3. Give a disadvantage for this language design choice.