Practical Scheme Programming
- by Ixmatus
It's been a few months since I've touched Scheme and decided to implement a command line income partitioner using Scheme.
My initial implementation used plain recursion over the continuation, but I figured a continuation would be more appropriate to this type of program. I would appreciate it if anyone (more skilled with Scheme than I) could take a look at this and suggest improvements. I'm that the multiple (display... lines is an ideal opportunity to use a macro as well (I just haven't gotten to macros yet).
(define (ab-income)
(call/cc
(lambda (cc)
(let
((out (display "Income: "))
(income (string->number (read-line))))
(cond
((<= income 600)
(display (format "Please enter an amount greater than $600.00~n~n"))
(cc (ab-income)))
(else
(let
((bills (* (/ 30 100) income))
(taxes (* (/ 20 100) income))
(savings (* (/ 10 100) income))
(checking (* (/ 40 100) income)))
(display (format "~nDeduct for bills:---------------------- $~a~n" (real->decimal-string bills 2)))
(display (format "Deduct for taxes:---------------------- $~a~n" (real->decimal-string taxes 2)))
(display (format "Deduct for savings:-------------------- $~a~n" (real->decimal-string savings 2)))
(display (format "Remainder for checking:---------------- $~a~n" (real->decimal-string checking 2))))))))))
Invoking (ab-income) asks for input and if anything below 600 is provided it (from my understanding) returns (ab-income) at the current-continuation. My first implementation (as I said earlier) used plain-jane recursion. It wasn't bad at all either but I figured every return call to (ab-income) if the value was below 600 kept expanding the function.
(please correct me if that apprehension is incorrect!)
