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23 lines
1.1 KiB
23 lines
1.1 KiB
2 years ago
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Exercise 5.44: In this section we have focused
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on the use of the compile-time environment to produce lexical addresses. But
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there are other uses for compile-time environments. For instance, in
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Exercise 5.38 we increased the efficiency of compiled code by open-coding
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primitive procedures. Our implementation treated the names of open-coded
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procedures as reserved words. If a program were to rebind such a name, the
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mechanism described in Exercise 5.38 would still open-code it as a
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primitive, ignoring the new binding. For example, consider the procedure
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(lambda (+ * a b x y)
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(+ (* a x) (* b y)))
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which computes a linear combination of x and y. We might call it
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with arguments +matrix, *matrix, and four matrices, but the
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open-coding compiler would still open-code the + and the * in
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(+ (* a x) (* b y)) as primitive + and *. Modify the
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open-coding compiler to consult the compile-time environment in order to
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compile the correct code for expressions involving the names of primitive
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procedures. (The code will work correctly as long as the program does not
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define or set! these names.)
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