From 2956e6275afa2618499d52355e21f090d4582ff0 Mon Sep 17 00:00:00 2001
From: Lionel Henry <lionel.hry@gmail.com>
Date: Wed, 5 Aug 2020 09:31:56 +0200
Subject: [PATCH] Add `.simplify` argument in `accumulate2()`

Closes #774
---
 NEWS.md                      |  4 ++++
 R/reduce.R                   | 10 ++++++++--
 man/accumulate.Rd            |  4 ++--
 tests/testthat/test-reduce.R |  8 ++++----
 4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 8ffd670a..6034ee9d 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -11,6 +11,10 @@
   possible to disable the simplification by setting `.simplify` to
   `FALSE`.
 
+* `accumulate2()` gains a `.simplify` argument as well. It did not use
+  to simplify its output, but we've changed this default to
+  automatically simplify for consistency with `accumulate()`.
+
 * `accumulate()` now uses vctrs for simplifying the output. This
   ensures a more principled and flexible coercion behaviour.
 
diff --git a/R/reduce.R b/R/reduce.R
index ea969464..f01bfd4b 100644
--- a/R/reduce.R
+++ b/R/reduce.R
@@ -476,8 +476,14 @@ accumulate <- function(.x,
 }
 #' @rdname accumulate
 #' @export
-accumulate2 <- function(.x, .y, .f, ..., .init) {
-  reduce2_impl(.x, .y, .f, ..., .init = .init, .acc = TRUE)
+accumulate2 <- function(.x, .y, .f, ..., .init, .simplify = TRUE) {
+  res <- reduce2_impl(.x, .y, .f, ..., .init = .init, .acc = TRUE)
+
+  if (.simplify) {
+    acc_simplify(res)
+  } else {
+    res
+  }
 }
 
 accumulate_names <- function(nms, init, dir) {
diff --git a/man/accumulate.Rd b/man/accumulate.Rd
index 14c85525..185d4a7e 100644
--- a/man/accumulate.Rd
+++ b/man/accumulate.Rd
@@ -5,8 +5,6 @@
 \alias{accumulate2}
 \title{Accumulate intermediate results of a vector reduction}
 \usage{
-
-accumulate2(.x, .y, .f, ..., .init)
 accumulate(
   .x,
   .f,
@@ -15,6 +13,8 @@ accumulate(
   .dir = c("forward", "backward"),
   .simplify = TRUE
 )
+
+accumulate2(.x, .y, .f, ..., .init, .simplify = TRUE)
 }
 \arguments{
 \item{.x}{A list or atomic vector.}
diff --git a/tests/testthat/test-reduce.R b/tests/testthat/test-reduce.R
index 6bde58fa..e15f2172 100644
--- a/tests/testthat/test-reduce.R
+++ b/tests/testthat/test-reduce.R
@@ -172,8 +172,8 @@ test_that("basic accumulate2() works", {
   paste2 <- function(x, y, sep) paste(x, y, sep = sep)
 
   x <- c("a", "b", "c")
-  expect_equal(accumulate2(x, c("-", "."), paste2), list("a", "a-b", "a-b.c"))
-  expect_equal(accumulate2(x, c(".", "-", "."), paste2, .init = "x"), list("x", "x.a", "x.a-b", "x.a-b.c"))
+  expect_equal(accumulate2(x, c("-", "."), paste2), c("a", "a-b", "a-b.c"))
+  expect_equal(accumulate2(x, c(".", "-", "."), paste2, .init = "x"), c("x", "x.a", "x.a-b", "x.a-b.c"))
 })
 
 test_that("can terminate accumulate2() early", {
@@ -187,8 +187,8 @@ test_that("can terminate accumulate2() early", {
   }
 
   x <- c("a", "b", "c")
-  expect_equal(accumulate2(x, c("-", "."), paste2), list("a", "a-b"))
-  expect_equal(accumulate2(x, c(".", "-", "."), paste2, .init = "x"), list("x", "x.a", "x.a-b"))
+  expect_equal(accumulate2(x, c("-", "."), paste2), c("a", "a-b"))
+  expect_equal(accumulate2(x, c(".", "-", "."), paste2, .init = "x"), c("x", "x.a", "x.a-b"))
 })
 
 test_that("accumulate2() forces arguments (#643)", {