Dynamic Spreadsheet Assignment
Contents
Motivation
Code To Use
- #t true
- #f false
- define-syntax
- lambda
- procedure?
- procedure-arity number of arguments a function takes Arity on Wikipedia
- pair?
- cons
- car
- cdr
- values
- raise
Code To Implement
file: | src/main/racket/spreadsheet/spreadsheet.rkt | ![]() |
functions: | to-cell csv->spreadsheet row-count row-at sheet sum-row |
string->cell
(define (string->cell s) (error 'not-yet-implemented))
csv->spreadsheet
define a MACRO thunk-that
which takes a parameter e
creates thunk. that is: wraps e
in a zero argument function.
(define-syntax-rule (thunk-that e) (error 'not-yet-implemented))
Thunks are useful for delaying the evaluation of expressions. As such thunk-that
must be declared as a macro and not a function. Unlike Haskell which has lazy evaluation, Racket (and most other languages) eagerly evaluates function arguments.
row-count
define a function dethunk
which takes a thunk parameter e
and returns the result of invoking e
.
(define (dethunk-that thunk) (error 'not-yet-implemented))
If thunking and expression wraps an expression in a single argument function, then de-thunking is simply calling that function.
If the parameter thunk
is not a thunk?
then dethunk-that
should raise an argument error.
NOTE: It may seem unnecessary to use dethunk-that
when implementing Lab4, when you could simply (thunk)... that is "call the thunk". Still, you are encouraged to use dethunk-that
as a bit of verbosity can sometimes help in debugging a sea already full of parentheses.
row-at
sum-row
define a function destream
which takes a stream
parameter and a pair of the next answer and the next stream.
(define (destream stream) (error 'not-yet-implemented))
Test
file: | spreadsheet_test.rkt | ![]() |
source folder: | src/test/racket/spreadsheet |
note: ensure that you have removed all printing to receive credit for any assignment.