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[Scheme-reports] DELAY AND FORCE
- To: Alex Shinn <alexshinn@x>
- Subject: [Scheme-reports] DELAY AND FORCE
- From: Andre van Tonder <andre@x>
- Date: Sat, 23 Apr 2011 18:19:31 -0400 (EDT)
- Cc: scheme-reports@x
- In-reply-to: <BANLkTik2QF-u=58SLtQDTTWnx6htQxhqXA@mail.gmail.com>
- References: <BANLkTi=hSfKrHo13BUMP==SNPCX-+As0HQ@mail.gmail.com> <BANLkTi=kSqWZpF-fAPObreiuAf9FxPb85w@mail.gmail.com> <BANLkTik2QF-u=58SLtQDTTWnx6htQxhqXA@mail.gmail.com>
p 14: Waddell showed a long time ago that DELAY and FORCE are not
the correct primitives for lazy evaluation in a strict language.
In short, it is impossible to write properly iterative lazy programs that
don't have memory leaks with just DELAY and FORCE. This is discussed in
more detail in SRFI 45 and references therein.
Since the original Scheme report took so much trouble to get iterative
tail recursion right, it would be a shame if the report got lazy
evaluation wrong again - I believe DELAY and FORCE were removed from
(R6RS BASE) for this reason among others. I would suggest removing
DELAY and FORCE from WG1 as well.
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