R help - Jan 2009 - lazy evaluation question

I've been going back to old difficult R-list "evaluation" emails
that I
save  in order to understand evaluation better and below still confuses 
me. Could someone explain why A) works and B) doesn't. A variant of 
below is in the  Pat's Inferno book also but I'm still not clear on what
is happening. Thanks.

f <- function() {
   # FORCING i here doesn't help
   i*i
}

F <- function(i) {
   force(i)
   print(f())
   }

A) THIS WORKS
for ( i in 1:4 ) {
   F(i)
}

B) THIS DOESN'T
lapply(1:4,function(i) F(i))

Note that

rm(i)
for(j in 1:4) F(j)

raises an error due to scoping issues.

On Sun, Jan 18, 2009 at 10:02 PM,  <markleeds at verizon.net>
wrote:
> I've been going back to old difficult R-list "evaluation"
emails that I save
>  in order to understand evaluation better and below still confuses me.
Could
> someone explain why A) works and B) doesn't. A variant of below is in
the
>  Pat's Inferno book also but I'm still not clear on what is
happening.
> Thanks.
>
> f <- function() {
>  # FORCING i here doesn't help
>  i*i
> }
>
> F <- function(i) {
>  force(i)
>  print(f())
>  }
>
> A) THIS WORKS
> for ( i in 1:4 ) {
>  F(i)
> }
>
> B) THIS DOESN'T
> lapply(1:4,function(i) F(i))
>
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