Add is_empty to dict

2 files changed, 35 insertions, 0 deletions

diff --git a/src/gleam/dict.gleam b/src/gleam/dict.gleam
index f44daa3..99ca30c 100644
--- a/src/gleam/dict.gleam
+++ b/src/gleam/dict.gleam
@@ -35,6 +35,24 @@ pub type Dict(key, value)
 @external(javascript, "../gleam_stdlib.mjs", "map_size")
 pub fn size(dict: Dict(k, v)) -> Int
 
+/// Determines whether or not the dict is empty.
+///
+/// ## Examples
+///
+/// ```gleam
+/// new() |> is_empty
+/// // -> True
+/// ```
+///
+/// ```gleam
+/// new() |> insert("b", 1) |> is_empty
+/// // -> False
+/// ```
+///
+pub fn is_empty(dict: Dict(a, b)) -> Bool {
+  dict == new()
+}
+
 /// Converts the dict to a list of 2-element tuples `#(key, value)`, one for
 /// each key-value pair in the dict.
 ///
diff --git a/test/gleam/dict_test.gleam b/test/gleam/dict_test.gleam
index 0bcb334..9ec1475 100644
--- a/test/gleam/dict_test.gleam
+++ b/test/gleam/dict_test.gleam
@@ -349,6 +349,23 @@ pub fn size_test() {
   |> should.equal(18)
 }
 
+pub fn is_empty_test() {
+  dict.new()
+  |> dict.is_empty()
+  |> should.be_true()
+
+  dict.new()
+  |> dict.insert(1, 10)
+  |> dict.is_empty()
+  |> should.be_false()
+
+  dict.new()
+  |> dict.insert(1, 10)
+  |> dict.delete(1)
+  |> dict.is_empty()
+  |> should.be_true()
+}
+
 // https://github.com/gleam-lang/stdlib/issues/435
 pub fn peters_bug_test() {
   dict.new()