simplify list0() (#55)

R/list.R

@@ -7,27 +7,16 @@
 #' @examples
 #' try(list(1, ))
 #' list0(1, )
+#' try(list(a = 1, ))
 #' list0(a = 1, )
+#' try(list(a = 1, , c = 3, ))
+#' list0(a = 1, , c = 3, )
 #' @export
 list0 <- function(...) {
-  mc <- match.call()
-  out <- list()
-  off <- 0L
-
-  for (i in seq_len(...length())) {
-    tryCatch(
-      out <- append(out, ...elt(i)),
-      error = function(e) {
-        if (!identical(e$message, "argument is missing, with no default")) {
-          e$call <- mc
-          stop(e)
-        }
-
-        assign("off", 1L, parent.frame()$parentenv)
-      }
-    )
-  }
-
-  names(out) <- names(mc)[-1L][seq_len(i - off)]
-  out
+  e <- as.list(substitute(list(...)))[-1L]
+  do.call(list, e[e != substitute()], envir = parent.frame(2))
 }
+
+#' @export
+#' @rdname list0
+lst <- list0