Both CHICKEN 6 and CHICKEN 5 with the r7rs egg exhibit unexpected
behavior with the following set of libraries (this file is referred to
as "tmp.scm"):
(define-library (hascheme prelude)
(import (scheme base) (scheme lazy))
(export hs:promise? hs:delay hs:delay-force hs:force)
(begin
(define-record-type <hascheme-promise>
(%hascheme-promise promise)
hs:promise?
(promise %get-raw-promise))
(define-syntax hs:delay-force
(syntax-rules ()
((_ expr)
(%hascheme-promise (delay-force expr)))))
(define-syntax hs:delay
(syntax-rules ()
((_ expr)
(%hascheme-promise (delay expr)))))
(define (hs:force promise)
(if (hs:promise? promise)
(force (%get-raw-promise promise))
promise))))
(define-library (my-other-library)
(import (scheme base)
(rename (hascheme prelude)
(hs:delay delay)
(hs:force force)
(hs:delay-force delay-force)
(hs:promise? promise?)))
(export delay force delay-force promise? !)
(begin
(define ! force)))
When the following is done in a REPL:
(load "tmp.scm")
(import (hascheme prelude))
(define x 10)
(hs:force (hs:delay (set! x 100)))
x
one gets the intended result 100.
But if the following is done in a REPL:
(load "tmp.scm")
(import (my-other-library))
(define x 10)
(force (delay (set! x 100)))
x
Then x is not changed, even though "force" and "delay" should be exactly
"hs:force" and "hs:delay".
The behavior likely occurs in compiled code too. The project from which
I pulled this reduced example exhibits the same errors when compiled,
but I have not tried the minimal example compiled.
-- Peter McGoron
