From d27dc4d69bda7e98c33ad99955972f6e163b608c Mon Sep 17 00:00:00 2001
From: Kevin Joiner <10265309+KevinJoiner@users.noreply.github.com>
Date: Mon, 19 Aug 2024 09:29:04 -0400
Subject: [PATCH] give sets a usable zero value

---
 set/set.go      | 11 +++++++++--
 set/set_test.go | 11 +++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/set/set.go b/set/set.go
index d66b30d..d43e168 100644
--- a/set/set.go
+++ b/set/set.go
@@ -13,12 +13,19 @@ func New[A comparable](as ...A) Set[A] {
 }
 
 // Add adds an element to the set.
-func (s Set[A]) Add(a A) {
-	s[a] = struct{}{}
+func (s *Set[A]) Add(a A) {
+	if *s == nil {
+		*s = New(a)
+		return
+	}
+	(*s)[a] = struct{}{}
 }
 
 // Contains checks if an element is in the set.
 func (s Set[A]) Contains(a A) bool {
+	if s == nil {
+		return false
+	}
 	_, ok := s[a]
 	return ok
 }
diff --git a/set/set_test.go b/set/set_test.go
index 56ca99d..0ff183c 100644
--- a/set/set_test.go
+++ b/set/set_test.go
@@ -21,4 +21,15 @@ func TestSet(t *testing.T) {
 	if s.Contains("xpp") {
 		t.Error("set contains xpp but this was never added")
 	}
+
+	var s2 Set[int]
+	s2.Add(2)
+	if !s2.Contains(2) {
+		t.Error("expected set to contain 2 but it did not")
+	}
+
+	var s3 Set[uint32]
+	if s3.Contains(2) {
+		t.Error("expected set to not contain 2 but it did")
+	}
 }