Difference between revisions of "Thunks and Streams Assignment"
| Line 18: | Line 18: | ||
=Code To Implement= | =Code To Implement= | ||
==Thunk Utilities== | ==Thunk Utilities== | ||
| − | + | ===thunk?=== | |
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. | ||
| + | ===thunk MACRO=== | ||
define a macro <code>thunk</code> which creates thunk | define a macro <code>thunk</code> which creates thunk | ||
| + | ===dethunk=== | ||
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>. | ||
Revision as of 18:08, 2 July 2019
Contents
Code To Use
Code To Implement
Thunk Utilities
thunk?
define a function thunk? which returns #t if the specified parameter is a thunk, #f otherwise.
thunk MACRO
define a macro thunk which creates thunk
dethunk
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...
