You are looking at historical revision 13808 of this page. It may differ significantly from its current revision.
Primitives for Expressing Iterative Lazy Algorithms
Extends the interpretation of a promise to include lazy and eager promises.
For more information see SRFI 45.
delay[syntax] (delay EXPRESSION)
Returns a promise, a delayed evaluation of EXPRESSION.
Mentioned only for completeness.
lazy[syntax] (lazy EXPRESSION)
Returns a promise for EXPRESSION.
The promise will be iteratively forced, overwriting the promise at each step before the next iteration, so as to avoid storage leaks.
eager[syntax] (eager EXPRESSION)
Returns a promise but immediately evaluates EXPRESSION.
Not much of a promise, more of a boxed value. For exposition purposes in algorithms.
force[procedure] (force OBJECT)
Assuming the OBJECT is some kind of promise, returns the result of the delayed evaluation.
promise?[procedure] (promise? OBJECT)
Some kind of promise?
recursive-promise?[procedure] (recursive-promise? OBJECT)
lazy-promise?[procedure] (lazy-promise? OBJECT)
Lazy recursive promise?
eager-promise?[procedure] (eager-promise? OBJECT)
Eager recursive promise?
(require-library srfi-45) ... (import srfi-45)
- Unlike the reference implementation this version does not redefine delay.
Bugs and Limitations
- Chicken 4 release.
Copyright (C) 2009 Kon Lovett. All rights reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the Software), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED ASIS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.