Remove check for primitive/builtin in as_mapper.default() to improve performance

NEWS.md

@@ -1,5 +1,7 @@
 # purrr (development version)
 
+* `as_mapper.default()` optimized by removing special named argument handling for primitive functions (@mtcarsalot, #1088).
+
 * `list_flatten()` gains an `is_node` parameter taking a predicate function that determines whether an input element is a node or a leaf (@salim-b, #1179).
 
 * `in_parallel()` now accepts objects, including helper functions, supplied to `...` for all locally-defined functions (#1208).

R/map-mapper.R

@@ -43,18 +43,7 @@ as_mapper <- function(.f, ...) {
 
 #' @export
 as_mapper.default <- function(.f, ...) {
-  if (typeof(.f) %in% c("special", "builtin")) {
-    .f <- rlang::as_closure(.f)
-
-    # Workaround until fixed in rlang
-    if (is_reference(fn_env(.f), base_env())) {
-      environment(.f) <- global_env()
-    }
-
-    .f
-  } else {
-    rlang::as_function(.f)
-  }
+  rlang::as_function(.f)
 }
 
 #' @export

tests/testthat/test-map-mapper.R

@@ -51,7 +51,7 @@ test_that("can supply length > 1 vectors", {
 # primitive functions --------------------------------------------------
 
 test_that("primitive functions are wrapped", {
-  expect_identical(as_mapper(`-`)(.y = 10, .x = 5), -5)
+  expect_identical(as_mapper(`-`)(.y = 10, .x = 5), 5) # positional matching, not by name
   expect_identical(as_mapper(`c`)(1, 3, 5), c(1, 3, 5))
 })