From a263ddee5ea10d822bb26db12e96661685020927 Mon Sep 17 00:00:00 2001
From: Richard Feldman <oss@rtfeldman.com>
Date: Sun, 16 Nov 2025 23:53:25 -0500
Subject: [PATCH] Make List be a phantom type

---
 src/build/roc/Builtin.roc | 2 +-
 src/types/store.zig       | 2 +-
 src/types/types.zig       | 1 -
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/build/roc/Builtin.roc b/src/build/roc/Builtin.roc
index c36b5a4601..3c664a051e 100644
--- a/src/build/roc/Builtin.roc
+++ b/src/build/roc/Builtin.roc
@@ -6,7 +6,7 @@ Builtin :: [].{
 		contains = |_str, _other| True
 	}
 
-	List :: [ProvidedByCompiler].{
+	List(_item) :: [ProvidedByCompiler].{
 		len : List(_item) -> U64
 		is_empty : List(_item) -> Bool
 		concat : List(item), List(item) -> List(item)
diff --git a/src/types/store.zig b/src/types/store.zig
index cae9c497d9..67cc8ab125 100644
--- a/src/types/store.zig
+++ b/src/types/store.zig
@@ -1366,7 +1366,7 @@ test "Store comprehensive CompactWriter roundtrip" {
     try std.testing.expectEqual(Content{ .structure = .{ .str = {} } }, deser_str.desc.content);
 
     const deser_list = deserialized.resolveVar(list_var);
-    // List is now a nominal type
+    // List is a nominal type
     try std.testing.expect(deser_list.desc.content.structure == .nominal_type);
     const deser_nominal = deser_list.desc.content.structure.nominal_type;
     const deser_list_args = deserialized.sliceNominalArgs(deser_nominal);
diff --git a/src/types/types.zig b/src/types/types.zig
index 25f37695cf..04aa9408ed 100644
--- a/src/types/types.zig
+++ b/src/types/types.zig
@@ -395,7 +395,6 @@ pub const TypeIdent = struct {
 pub const FlatType = union(enum) {
     str,
     box: Var,
-    // NOTE: .list and .list_unbound have been removed - List is now a nominal type
     record: Record,
     record_unbound: RecordField.SafeMultiList.Range,
     tuple: Tuple,