On 5 June 2012 17:47, Jamison Hope <jrh@theptrgroup.com> wrote:
Back through the looking glass. So: what is special about procedure
bindings?
I found a new data point just now, but I'm struggling to see how I can
fix the problem with it:
(from kawa-1.12.jar)
#|kawa:1|# (define (myfun) 'outer)
#|kawa:2|# (let ((myfun (lambda () 'inner)))
#|(---:3|# (myfun))
inner
#|kawa:4|# (myfun)
outer
#|kawa:5|# (apply myfun '())
outer
#|kawa:6|# (let ((myfun (lambda () 'inner)))
#|(---:7|# (apply myfun '()))
inner
#|kawa:8|# (myfun)
inner
#|kawa:9|# (apply myfun '())
inner
Note that it's the APPLY that clobbers the top-level function binding.
The only thing I can see that is different with these two approaches
comes from CallContext#runUnitlDone, the:
Procedure proc = this.proc
...
this.proc = null
proc.apply(this)
When (myfun) is the body of the let, <procedure myfun> is does not go
through the above operations and all is good. My (apply myfun '()) is
the body of the let, <procedure myfun> *does* go through the above
operations (that is, this.proc = null followed by proc.apply), and it
*does* clobber the top-level binding. I'm stuggling to see where this
clobbering is happening though!
I'll continue scratching my head, just thought that was an interesting
data point.