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[Scheme-reports] Formal Comment: what is the required behavior of 'lazy'?
- To: scheme-reports@x
- Subject: [Scheme-reports] Formal Comment: what is the required behavior of 'lazy'?
- From: Richard Kelsey <kelsey@x>
- Date: Wed, 27 Jun 2012 18:58:57 +0000 (UTC)
Submitter's name: Richard Kelsey
Submitter's email: kelsey at s48.org
Relevant draft: r7rs draft 6
Relevant section of draft: Derived expression types
Summary: 'lazy' is underspecified
The description of (lazy <expression>) says
The returned promise, when forced, will evaluate to whatever the
original promise would have evaluated to if it had been forced.
This describes what
(delay (force <expression>))
does. On the other hand, the description of the stream-filter example
says that '(lazy <x>)' is not the same as '(delay (force <x>))'. If
this is true, the description of 'lazy' needs to say what the
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