tm结合语料库列表

我有一个URL列表,我已经获取了webcontent,并将其包含在tm语料库中:

library(tm)
library(XML)

link <- c(
"http://www.r-statistics.com/tag/hadley-wickham/",                                                      
"http://had.co.nz/",                                                                                    
"http://vita.had.co.nz/articles.html",                                                                  
"http://blog.revolutionanalytics.com/2010/09/the-r-files-hadley-wickham.html",                          
"http://www.analyticstory.com/hadley-wickham/"  
)               

create.corpus <- function(url.name){
doc=htmlParse(url.name)
parag=xpathSApply(doc,'//p',xmlValue)
if (length(parag)==0){
  parag="empty"
}
cc=Corpus(VectorSource(parag))
meta(cc,"link")=url.name
return(cc)
}

link=catch$url
cc <- lapply(link, create.corpus)

这给了我一个语料库的"大列表",每个URL一个.将它们逐一组合起来:

x=cc[[1]]
y=cc[[2]]
z=c(x,y,recursive=T) # preserved metadata
x;y;z
# A corpus with 8 text documents
# A corpus with 2 text documents
# A corpus with 10 text documents

但这对于拥有几千个语料库的列表来说变得不可行.那么如何在维护元数据的同时将语料库列表合并到一个语料库中呢？