Difference between revisions of "Thunks and Streams Assignment"

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===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.
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 +
===stream-next===
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BONUS method not officially part of the studio but a good idea.
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 +
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

Code To Use

define-syntax

lambda

procedure?

procedure-arity

pair?

cons

car

cdr

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...