merge unnamed lists in merge_lists function

Unnamed lists can now be overriden by another config section (see rstudio#24)

R/merge.R

@@ -20,24 +20,32 @@ merge <- function(base_config, merge_config) {
 # recursively merge two lists (extracted from code used by rmarkdown
 # package to merge _output.yml, _site.yml, front matter, etc.:
 # https://github.com/rstudio/rmarkdown/blob/master/R/util.R#L174)
-merge_lists <- function (base_list, overlay_list, recursive = TRUE) {
-  if (length(base_list) == 0)
+merge_lists <- function (base_list, overlay_list, recursive = TRUE) 
+{
+  if (length(base_list) == 0) 
     overlay_list
-  else if (length(overlay_list) == 0)
+  else if (length(overlay_list) == 0) 
     base_list
   else {
     merged_list <- base_list
+
+    # merge named lists
     for (name in names(overlay_list)) {
       base <- base_list[[name]]
       overlay <- overlay_list[[name]]
-      if (is.list(base) && is.list(overlay) && recursive)
+      if (is.list(base) && is.list(overlay) && recursive) 
         merged_list[[name]] <- merge_lists(base, overlay)
       else {
         merged_list[[name]] <- NULL
-        merged_list <- append(merged_list,
-                              overlay_list[which(names(overlay_list) %in% name)])
+        merged_list <- append(merged_list, overlay_list[which(names(overlay_list) %in% 
+                                                                name)])
       }
     }
+
+    # merge unnamed lists
+    if (is.null(names(base_list)) && is.null(names(overlay_list))) {
+      merged_list <- overlay_list
+    }
     merged_list
   }
 }