In section 3.5.4 , i saw this block:

(define (integral delayed-integrand initial-value dt)
    (define int
        (cons-stream initial-value
            (let ((integrand (force delayed-integrand)))
                (add-streams (scale-stream integrand dt)

Normally if this was something like:

(define (stream-map proc s)
    (if (stream-null? s)
            (cons-stream (proc (stream-car s))
                (stream-map proc (stream-cdr s)))))

The stream-cdr s would be evaluated as (cons-stream (stream-car (cdr s)) delay<>) even when the actual call would be in a delay. ie even though the stream-map function itself is delayed, the arguments are pre-computed.

Then why is let not pre-computed?

What I think? I think let is a lambda function with no arguments, so its execution is delayed

Can someone please help me confirm this?



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