Difference between revisions of "Dynamic Spreadsheet Assignment"
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(Created page with "=Motivation= =Code To Use= * [https://docs.racket-lang.org/reference/booleans.html #t] true * [https://docs.racket-lang.org/reference/booleans.html #f] false * [https://docs....") |
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(error 'not-yet-implemented))</nowiki> | (error 'not-yet-implemented))</nowiki> | ||
| − | + | ==csv->spreadsheet== | |
define a '''MACRO''' <code>thunk-that</code> which takes a parameter <code>e</code> creates thunk. that is: wraps <code>e</code> in a zero argument function. | define a '''MACRO''' <code>thunk-that</code> which takes a parameter <code>e</code> creates thunk. that is: wraps <code>e</code> in a zero argument function. | ||
| Line 31: | Line 31: | ||
Thunks are useful for delaying the evaluation of expressions. As such <code>thunk-that</code> must be declared as a macro and not a function. Unlike [https://www.haskell.org/ Haskell] which has lazy evaluation, Racket (and most other languages) [https://en.wikipedia.org/wiki/Eager_evaluation eagerly evaluates] function arguments. | Thunks are useful for delaying the evaluation of expressions. As such <code>thunk-that</code> must be declared as a macro and not a function. Unlike [https://www.haskell.org/ Haskell] which has lazy evaluation, Racket (and most other languages) [https://en.wikipedia.org/wiki/Eager_evaluation eagerly evaluates] function arguments. | ||
| − | + | ==row-count== | |
define a function <code>dethunk</code> which takes a thunk parameter <code>e</code> and returns the result of invoking <code>e</code>. | define a function <code>dethunk</code> which takes a thunk parameter <code>e</code> and returns the result of invoking <code>e</code>. | ||
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NOTE: It may seem unnecessary to use <code>dethunk-that</code> when implementing Lab4, when you could simply (thunk)... that is "call the thunk". Still, you are encouraged to use <code>dethunk-that</code> as a bit of verbosity can sometimes help in debugging a sea already full of parentheses. | NOTE: It may seem unnecessary to use <code>dethunk-that</code> when implementing Lab4, when you could simply (thunk)... that is "call the thunk". Still, you are encouraged to use <code>dethunk-that</code> as a bit of verbosity can sometimes help in debugging a sea already full of parentheses. | ||
| − | + | ==row-at== | |
| − | + | ==sum-row== | |
define a function <code>destream</code> which takes a <code>stream</code> parameter and a pair of the next answer and the next stream. | define a function <code>destream</code> which takes a <code>stream</code> parameter and a pair of the next answer and the next stream. | ||
(define (destream stream) | (define (destream stream) | ||
(error 'not-yet-implemented)) | (error 'not-yet-implemented)) | ||
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=Test= | =Test= | ||
{{RacketUnitTest|spreadsheet_test|spreadsheet}} | {{RacketUnitTest|spreadsheet_test|spreadsheet}} | ||
Revision as of 05:39, 30 March 2022
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 |
to-cell
define a function thunk? which returns whether the specified parameter is a thunk or not.
(define (thunk? th)
(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 | Test |
| source folder: | src/test/racket/spreadsheet |
note: ensure that you have removed all printing to receive credit for any assignment.
