Lab Quiz Solutions, Foundations of Computing, Week 4 (Thursday) -- Oct 19, 2000

1. For each expression, write down its type. Give the most specific type you can: for the expression 8, number is a better answer than word.

   1. x -- Symbol, atom or word
      
      
   2. (x) -- List
      
      
   3. '(x y z) -- List
      
      
   4. 8 -- Number or integer (symbol etc. are less specific)
      
      
   5. + -- Procedure (symbol etc. are less specific)
      
      
   6. (+ 9 10) -- List
      
      
   7. (lambda (x) (word 'super- x)) -- List
      
      

2. For each procedure, write down the types of its arguments and its result. Give the most specific types you can.

   1. + -- Arguments: number, Result: number
      
      
   2. word -- Arguments: word, Result: word
      
      
   3. sentence -- Arguments: word or sentence, Result: sentence
      
      
   4. every -- Argument 1: procedure, Argument 2: List, Result: List
      
      

3. For each expression, write down whether it can be evaluated or not (do not write down the value).

   1. (+ 1 2) -- Yes
      
      
   2. (+ 1 'two) -- No, second argument is not a number, it's just a symbol
      
      
   3. (+ 1 (2)) -- No, second argument is not a number, it's a list
      
      
   4. (word 1 2) -- Yes
      
      
   5. (word 'super 'stitious) -- Yes
      
      
   6. (word '(super stitious)) -- No, argument is not a word, it's a list
      
      
   7. (every 'super '(duper sonic)) -- No, first argument is not a procedcure
      
      
   8. (every (lambda (x) (word 'super- x)) '(duper sonic)) -- Yes
      
      
   9. (every '(lambda (x) (word 'super- x)) '(duper sonic)) -- No, first argument is not a procedure, it's just a list