Difference between revisions of "Thunks and Streams Assignment"
Line 39: | Line 39: | ||
===next-stream-from-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-next=== | ||
+ | BONUS method not officially part of the studio but a good idea. | ||
+ | |||
+ | define a function <code>stream-next</code> which takes a stream parameter and returns a pair of values for the next value and the next stream. | ||
===stream-cons=== | ===stream-cons=== |
Revision as of 16:00, 8 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-next
BONUS method not officially part of the studio but a good idea.
define a function stream-next
which takes a stream parameter and returns a pair of values for the next value and the next 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
flip-flop-stream
define flip-flop-stream
which produces #t #f #t #f #t #f #t #f...