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MzScheme implements delay as a macro that expands to
make-promise. The force procedure
can only be applied to values returned by make-promise, and
promises are never implicitly forced.
- (make-promise thunk) returns a new
promise, where thunk is a procedure of zero arguments.
- (promise? v) returns #t if
v is a proimise created by make-promise or #f
otherwise.
PLT