Please Try These Problems on Your Own Before You Read the Solutions –
You
Will Get Much More From Them That Way!
(Many of these problems are borrowed from TA Lisa)
Please note that solutions were derived on Dr.Scheme for Windows –
There may be slight differences between these answers and those of MacGambit.
(define (fish meal) ‘whatever)
(define five 5)
(define (six) 6)
What –exactly- is the variable ‘fish’ bound to?__A function that takes 1 arg and always returns ‘whatever.
What –exactly- is the variable ‘five’ bound to?__The number 5.
What –exactly- is the variable ‘six’
bound to?___A procedure that always returns the number 6.
Given the above definitions, what value and type would the following scheme expressions return? (Some may be errors.)
|
>(+ ‘1 ‘2 ‘3) 6 |
>(+ 1 2 3) 6 |
>(‘+ ‘1 ‘2 ‘3) Error-Expected Proc |
|
>(+) 0 |
>(*) 1 |
>(-) Error-proc ‘-‘ needs at least 1 argument |
|
>(first 2/6) 1 |
>(first ‘2/6) 1 |
>(bf 2/6) /3 |
|
>(bf 00012) 2 |
>(bf ‘00012) 2 |
>(bf ‘r0012) “0012” |
|
>(se ‘(fish fish) (fish fish)) (fish fish whatever) |
>(se (fish fish) (fish fish)) (whatever whatever) |
>(se ‘((fish fish) (fish fish))) Error-Arg is not a word or sentence. |
|
>six #<proc-six> |
>‘six six |
>(six) 6 |
|
>‘(six) (six) |
>‘’(six) ‘(six) |
>‘(‘six) (‘six) |
|
>five 5 |
>‘five five |
>(five) Error-Expected a proc |
|
>(= 1 ‘1) #t |
>(= six 6) Error-Expected a number |
>(= five 5) #t |
|
>(if (3) ‘yes ‘no) Error-Expected a proc, got a number (3) |
>(if 0 ‘yes ‘no) yes |
>(if “” ‘yes ‘no) yes |
|
>(if ‘() ‘yes no) yes |
>(let ((a 3)) a) 3 |
>(let ((five 6)) (+ five (six))) 12 |