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Functional Programming in Scheme
The Order of Evaluation
Delayed evaluation in Scheme

Scheme does not support normal-order reduction nor lazy evaluation

Scheme has an explicit primitive which delays an evaluation

(delay expr) => promise

(force promise) => value

y:/Kurt/Files/courses/prog3/prog3-03/sources/notes/includes/delay-force-principle.scmA principled implementation of delay and force in Scheme.

y:/Kurt/Files/courses/prog3/prog3-03/sources/notes/includes/delay-force.scmReal implementations of delay.

The first definition uses the R5RS macro facility, whereas the last one uses a more primitive macro facility, which happens to be supported in MzScheme.