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26 lines
721 B
26 lines
721 B
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Exercise 4.18: Consider an alternative strategy
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for scanning out definitions that translates the example in the text to
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(lambda ⟨vars⟩
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(let ((u '*unassigned*)
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(v '*unassigned*))
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(let ((a ⟨e1⟩)
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(b ⟨e2⟩))
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(set! u a)
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(set! v b))
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⟨e3⟩))
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Here a and b are meant to represent new variable names, created
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by the interpreter, that do not appear in the user’s program. Consider the
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solve procedure from 3.5.4:
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(define (solve f y0 dt)
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(define y (integral (delay dy) y0 dt))
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(define dy (stream-map f y))
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y)
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Will this procedure work if internal definitions are scanned out as shown in
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this exercise? What if they are scanned out as shown in the text? Explain.
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