From fbd541429ab4c04e680aeaea2e3f1540b44dca59 Mon Sep 17 00:00:00 2001
From: Louis Pilfold <louis@lpil.uk>
Date: Sun, 29 Aug 2021 15:08:06 +0100
Subject: Array map

---
 CHANGELOG.md                           |  2 +-
 src/gleam/javascript/array.gleam       |  3 +++
 test/gleam/javascript/array_test.gleam | 14 ++++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index af4285a..04012f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,4 +3,4 @@
 ## Unreleased
 
 - The `array` module was created with the `Array(element)` type and `to_list`,
-  `from_list` and `length` functions.
+  `from_list`, `map`, and `length` functions.
diff --git a/src/gleam/javascript/array.gleam b/src/gleam/javascript/array.gleam
index b2e5992..6c4819e 100644
--- a/src/gleam/javascript/array.gleam
+++ b/src/gleam/javascript/array.gleam
@@ -8,3 +8,6 @@ pub external fn from_list(List(element)) -> Array(element) =
 
 pub external fn length(Array(element)) -> Int =
   "../../ffi.js" "length"
+
+pub external fn map(Array(a), fn(a) -> b) -> Array(b) =
+  "../../ffi.js" "map"
diff --git a/test/gleam/javascript/array_test.gleam b/test/gleam/javascript/array_test.gleam
index 2f5e627..2f149a5 100644
--- a/test/gleam/javascript/array_test.gleam
+++ b/test/gleam/javascript/array_test.gleam
@@ -17,3 +17,17 @@ pub fn length_test() {
     array.from_list([])
     |> array.length
 }
+
+pub fn map_test() {
+  assert [] =
+    []
+    |> array.from_list
+    |> array.map(fn(a) { a + 1 })
+    |> array.to_list
+
+  assert [2, 3, 4] =
+    [1, 2, 3]
+    |> array.from_list
+    |> array.map(fn(a) { a + 1 })
+    |> array.to_list
+}
-- 
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