Exercise 3.50 · 习题

Exercise 3.50: Complete the following
definition, which generalizes stream-map to allow procedures that take
multiple arguments, analogous to map in 2.2.1,
Footnote 78.

(define (stream-map proc . argstreams)

(if (⟨??⟩ (car argstreams))

the-empty-stream

(⟨??⟩

(apply proc (map ⟨??⟩ argstreams))

(apply stream-map

(cons proc

(map ⟨??⟩

argstreams))))))

练习 3.50：补全以下定义。该定义将 stream-map 推广为可接受多个参数的过程，类似于 2.2.1 节脚注 78 中的 map。

(define (stream-map proc . argstreams)
(if (⟨??⟩ (car argstreams))
the-empty-stream
(⟨??⟩
(apply proc (map ⟨??⟩ argstreams))
(apply stream-map
(cons proc
(map ⟨??⟩
argstreams))))))