Difference between revisions of "Thunks and Streams Assignment"
| Line 29: | Line 29: | ||
==Stream Utilities== | ==Stream Utilities== | ||
| + | ===plausible-stream?=== | ||
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. | ||
WARNING: what could happen if you called <code>plausible-stream?</code> recursively on the <code>cdr</code>? | WARNING: what could happen if you called <code>plausible-stream?</code> recursively on the <code>cdr</code>? | ||
| + | ===next-value-from-stream=== | ||
define a function <code>next-value-from-stream</code> which takes a stream parameter and returns the next value of that stream. | define a function <code>next-value-from-stream</code> which takes a stream parameter and returns the next value of that stream. | ||
| + | ===next-stream-from-stream=== | ||
define a function <code>next-stream-from-stream</code> which takes a stream parameter and returns the next stream of that stream. | define a function <code>next-stream-from-stream</code> which takes a stream parameter and returns the next stream of that stream. | ||
| + | ===stream-cons=== | ||
define a function <code>stream-cons</code> which takes two parameters <code>value</code> and <code>stream-prime</code>. if the specified <code>stream-prime</code> parameter is not a thunk then an error should be raised: | define a function <code>stream-cons</code> which takes two parameters <code>value</code> and <code>stream-prime</code>. if the specified <code>stream-prime</code> parameter is not a thunk then an error should be raised: | ||
Revision as of 18:09, 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
plausible-stream?
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?
next-value-from-stream
define a function next-value-from-stream which takes a stream parameter and returns the next value of that stream.
next-stream-from-stream
define a function next-stream-from-stream which takes a stream parameter and returns the next stream of that stream.
stream-cons
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...
