Difference between revisions of "Thunks and Streams Assignment"
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| − | =Thunk Utilities= | + | =Code To Use= |
| + | [https://docs.racket-lang.org/reference/define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define-syntax%29%29 define-syntax] | ||
| + | |||
| + | =Code To Implement= | ||
| + | ==Thunk Utilities== | ||
define a function <code>thunk?</code> which returns #t if the specified parameter is a thunk, #f otherwise. | define a function <code>thunk?</code> which returns #t if the specified parameter is a thunk, #f otherwise. | ||
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define a function <code>dethunk</code> which takes a thunk parameter <code>th</code> and returns the result of invoking <code>th</code>. | define a function <code>dethunk</code> which takes a thunk parameter <code>th</code> and returns the result of invoking <code>th</code>. | ||
| − | =Stream Utilities= | + | ==Stream Utilities== |
define a function <code>plausible-stream?</code> which returns #t if the specified parameter is a thunk which when invoked returns a pair whose cdr is a thunk, #f otherwise. | define a function <code>plausible-stream?</code> which returns #t if the specified parameter is a thunk which when invoked returns a pair whose cdr is a thunk, #f otherwise. | ||
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WARNING: what could happen if you called <code>plausible-stream?</code> on <code>stream-prime</code>? | WARNING: what could happen if you called <code>plausible-stream?</code> on <code>stream-prime</code>? | ||
| − | =Stream App= | + | ==Stream App== |
define <code>flip-flop-stream</code> which produces #t #f #t #f #t #f #t #f... | define <code>flip-flop-stream</code> which produces #t #f #t #f #t #f #t #f... | ||
Revision as of 18:03, 2 July 2019
Code To Use
Code To Implement
Thunk Utilities
define a function thunk? which returns #t if the specified parameter is a thunk, #f otherwise.
define a macro thunk which creates thunk
define a function dethunk which takes a thunk parameter th and returns the result of invoking th.
Stream Utilities
define a function plausible-stream? which returns #t if the specified parameter is a thunk which when invoked returns a pair whose cdr is a thunk, #f otherwise.
WARNING: what could happen if you called plausible-stream? recursively on the cdr?
define a function next-value-from-stream which takes a stream parameter and returns the next value of that stream.
define a function next-stream-from-stream which takes a stream parameter and returns the next stream of that stream.
define a function stream-cons which takes two parameters value and stream-prime. if the specified stream-prime parameter is not a thunk then an error should be raised:
(raise (error "not a thunk" stream-prime))
WARNING: what could happen if you called plausible-stream? on stream-prime?
Stream App
define flip-flop-stream which produces #t #f #t #f #t #f #t #f...
