Re: [R] Inf and lazy evaluation

2012-05-15 Thread peter dalgaard
On May 15, 2012, at 07:25 , R. Michael Weylandt wrote: > The only place I know lazy evaluation really is visible and widely > used is in the passing of function arguments. It's what allows magic > like > > zz <- 1:5 > plot(zz) > > to know your variable was called "zz." This is actually *not* l

Re: [R] Inf and lazy evaluation

2012-05-15 Thread Stefan Evert
> Oh, what is this world coming to when you can't count on laziness to > be lazy. ;) I should probably stop reading about Haskell and their > lazy way of doing things. Haskell would still have to check an infinite number of potential files on your hard disk, because it can't now when it's seen

Re: [R] Inf and lazy evaluation

2012-05-14 Thread R. Michael Weylandt
The only place I know lazy evaluation really is visible and widely used is in the passing of function arguments. It's what allows magic like zz <- 1:5 plot(zz) to know your variable was called "zz." It can also show up in some places through the promise mechanism, but you have to do a little bit

Re: [R] Inf and lazy evaluation

2012-05-14 Thread J Toll
Thank you all for the replies. On Mon, May 14, 2012 at 2:45 PM, R. Michael Weylandt wrote: > R is lazy, but not quite that lazy ;-) Oh, what is this world coming to when you can't count on laziness to be lazy. ;) I should probably stop reading about Haskell and their lazy way of doing things.

Re: [R] Inf and lazy evaluation

2012-05-14 Thread R. Michael Weylandt
R is lazy, but not quite that lazy ;-) It's likely much easier to do this with regexps something like list.files()[grepl(paste0(filename, "-"[0123456789]+""), list.files())] Michael On Mon, May 14, 2012 at 3:34 PM, J Toll wrote: > Hi, > > I have a question involving Inf, lazy evaluation, and

Re: [R] Inf and lazy evaluation

2012-05-14 Thread Bert Gunter
?list.files -- Bert On Mon, May 14, 2012 at 12:34 PM, J Toll wrote: > Hi, > > I have a question involving Inf, lazy evaluation, and maybe argument > recycling.  I have a directory where I am trying to check for the > existence of files of a certain pattern, basically something like > "filename-

[R] Inf and lazy evaluation

2012-05-14 Thread J Toll
Hi, I have a question involving Inf, lazy evaluation, and maybe argument recycling. I have a directory where I am trying to check for the existence of files of a certain pattern, basically something like "filename-#", where # is an integer. I can do something like this, which works. file.exists