add drop function to set module

2 files changed, 11 insertions, 0 deletions

diff --git a/src/gleam/set.gleam b/src/gleam/set.gleam
index 66b8378..2440986 100644
--- a/src/gleam/set.gleam
+++ b/src/gleam/set.gleam
@@ -199,6 +199,10 @@ pub fn filter(
   Set(map.filter(in: set.map, for: fn(m, _) { property(m) }))
 }
 
+pub fn drop(from set: Set(member), drop disallowed: List(member)) -> Set(member) {
+  list.fold(over: disallowed, from: set, with: delete)
+}
+
 /// Creates a new map from a given map, only including any members which are in
 /// a given list.
 ///
diff --git a/test/gleam/set_test.gleam b/test/gleam/set_test.gleam
index c771951..aae5256 100644
--- a/test/gleam/set_test.gleam
+++ b/test/gleam/set_test.gleam
@@ -80,6 +80,13 @@ pub fn take_test() {
   |> should.equal(set.from_list([1, 3]))
 }
 
+pub fn drop_test() {
+  ["a", "b", "c"]
+  |> set.from_list
+  |> set.drop(["a", "b", "d"])
+  |> should.equal(set.from_list(["c"]))
+}
+
 pub fn union_test() {
   set.union(set.from_list([1, 2]), set.from_list([2, 3]))
   |> set.to_list