1. All compilers translate to machine language. F
2. All programming language implementations are compilers. F
3. A simple value is a value that has no visible internal structure. T
4. Integers are typically considered complex values. F
5. A data structure that changes over time is not considered to be a value. T
6. A token can only have one associated lexeme. F
7. A variable name is typically a single lexeme in a program. T
8. Backus-Naur Form is a notation for giving precise definitions of syntax. T
9. Pattern matching can be used to bind names by solving simple equations. T
10. In C++, every block begins at the start of a function, and ends at the end of the function. F

Possible consequences:

• The definition is very difficult to understand.
• If there is a bug in the implementation, it cannot be fixed.
• It is impossible to have partially defined features, such as an undefined order of evaluation of certain expressions.

It is easy to extend sequences by adding values to the start. Also, the linked representation permits structure sharing, which sometimes greatly reduces memory requirements. There are other advantages, such as the ability to add values into the middle of the sequence.

Random access and reduced memory requirements for individual lists are important advantages.

Shadowing occurs when a binding of an identifier hides another binding of the same identifier that would have been visible but for this new binding. It occurs when a binding is done in an inner scope. For example, in C++,

     {int x;
      ...
      {int x;
       ...
      }
    }
  

    <S> ::= <S> a
         |  a <S>
         |  a
  

             S                       S
            / \                     / \
           S   a                   a   S
           |                           |
           a                           a
         
  

    <S> ::= <F> a <S>
         |  b
    <F> ::= a <F>
         |  c
  
  

  
                             S
                            /|\
                           / | \
                          /  |  \
                         /   |   \
                        /    |    \
                       /     |     \
                      /      |      \
                     F       a       S
                    / \             /|\
                   a   F           / | \
                      / \         F  a  S
                     a   F        |     |
                         |        c     b
                         c