(let ((x 10))
   (display "the result is: ")
   (display x)
   (define x 42))
   (newline))

; SRFI 245: the result is 10
; SRFI 251: <it is an error>

According to this proposal, the result got to be 10 --
the equivalent R7RS body is nested as follows:

(let ((x 10))
  (display "the result is: ")
  (display x)
  (let ()
    (define x 42)
    (newline)))

SRFI-245, as I understand it, proposes different "translation":

(let ((x 10))
  (define x
    (begin
      (display "the result is: ")
      (display x)
      42))
  (newline))

... which "is an error" according to R7RS, giving an implementation
a lot of options on how to react (strictly speaking, printing 10 is
one of the options)

On Friday, December 1, 2023 8:54:24 PM (-05:00), Per Bothner wrote:

> Also consider:
>
> (let ((x 10))
> (display "the result is: ")
> (display x)
> (define x 42))
> (newline))
>
> I believe the result here should be undefined - but *not* 10.
>
> In Kawa (which implements 245 and does some flow analysis) you get:
> the result is: 42
> Howver, if you replaced '42' by the non-constant '(list 42)' you get:
> the result is: #!undefined
> In both cases you get a compile-time warning:
> x.scm:3:12: warning - variable 'x' may be uninitialized here