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Source for ticket #55
cc
changetime
2011-01-24 06:38:39
component
WG1 - Core
description
R5RS provides a simple mechanism for easy cases of lazy evaluation. It does not support generalized lazy evaluation, because all built-in procedures are eager whether they 'need' to be or not. The relevant identifiers are `delay` and `force`; they are not present in IEEE Scheme. SRFI 45 argues that this pair is insufficient for expressing common lazy algorithms in a way that preserves tail recursion, and adds `lazy` (equivalent to `(delay (force ...))`, but acting atomically) and `eager`. The semantics of `delay` and `force` remain downward compatible.
id
55
keywords
milestone
owner
alexshinn
priority
major
reporter
cowan
resolution
wontfix
severity
status
closed
summary
Lazy evaluation
time
2010-05-02 23:46:34
type
defect
Changes
Change at time 2011-01-24 06:38:39
author
cowan
field
comment
newvalue
WG1 voted to reject SRFI 55.
oldvalue
4
raw-time
1295822319000000
ticket
55
time
2011-01-24 06:38:39
Change at time 2011-01-24 06:38:39
author
cowan
field
resolution
newvalue
wontfix
oldvalue
raw-time
1295822319000000
ticket
55
time
2011-01-24 06:38:39
Change at time 2011-01-24 06:38:39
author
cowan
field
status
newvalue
closed
oldvalue
new
raw-time
1295822319000000
ticket
55
time
2011-01-24 06:38:39
Change at time 2010-11-15 09:59:39
author
alexshinn
field
comment
newvalue
Regarding the sample implementation from R5RS, it does
memoize via `make-promise` so there's no need to change it.
oldvalue
3
raw-time
1289786379000000
ticket
55
time
2010-11-15 09:59:39
Change at time 2010-10-18 11:27:04
author
cowan
field
comment
newvalue
oldvalue
2
raw-time
1287376024000000
ticket
55
time
2010-10-18 11:27:04
Change at time 2010-10-18 11:27:04
author
cowan
field
component
newvalue
WG1 - Core
oldvalue
WG2 - Base Library
raw-time
1287376024000000
ticket
55
time
2010-10-18 11:27:04
Change at time 2010-10-18 11:27:04
author
cowan
field
owner
newvalue
alexshinn
oldvalue
cowan
raw-time
1287376024000000
ticket
55
time
2010-10-18 11:27:04
Change at time 2010-05-02 23:48:57
author
cowan
field
comment
newvalue
I favor the SRFI 45 argument; see the SRFI itself for details.
I think the four identifiers should be in an optional module.
Editorial note: the sample implementation given in R4RS and R5RS does not conform to the specification (it doesn't memoize) and should be removed or replaced.
oldvalue
1
raw-time
1272818937000000
ticket
55
time
2010-05-02 23:48:57