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22 lines
684 B
22 lines
684 B
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Exercise 4.74: Alyssa P. Hacker proposes to use
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a simpler version of stream-flatmap in negate, lisp-value,
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and find-assertions. She observes that the procedure that is mapped
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over the frame stream in these cases always produces either the empty stream or
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a singleton stream, so no interleaving is needed when combining these streams.
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Fill in the missing expressions in Alyssa’s program.
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(define (simple-stream-flatmap proc s)
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(simple-flatten (stream-map proc s)))
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(define (simple-flatten stream)
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(stream-map ⟨??⟩
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(stream-filter ⟨??⟩
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stream)))
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Does the query system’s behavior change if we change it in this way?
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