From 14d897db35df9a3a96d27eb1d14b8b08f4b3cb48 Mon Sep 17 00:00:00 2001
From: David Blass <david@arktype.io>
Date: Mon, 23 Oct 2023 11:39:23 -0400
Subject: [PATCH] fix: extracted morph inference

---
 dev/configs/.changeset/heavy-melons-approve.md | 5 +++++
 dev/test/morph.test.ts                         | 4 ++++
 src/scopes/type.ts                             | 8 ++++++--
 3 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 dev/configs/.changeset/heavy-melons-approve.md

diff --git a/dev/configs/.changeset/heavy-melons-approve.md b/dev/configs/.changeset/heavy-melons-approve.md
new file mode 100644
index 0000000000..172ce67d92
--- /dev/null
+++ b/dev/configs/.changeset/heavy-melons-approve.md
@@ -0,0 +1,5 @@
+---
+"arktype": patch
+---
+
+Fix an issue causing some morphs to not be properly extracted when .infer(red)
diff --git a/dev/test/morph.test.ts b/dev/test/morph.test.ts
index bc49ac4947..94a842b8a1 100644
--- a/dev/test/morph.test.ts
+++ b/dev/test/morph.test.ts
@@ -285,6 +285,10 @@ describe("morph", () => {
             ]
         ])
     })
+    it("union with output", () => {
+        const t = type("number|parsedNumber")
+        attest(t.infer).typed as number
+    })
     it("double intersection", () => {
         attest(() => {
             scope({
diff --git a/src/scopes/type.ts b/src/scopes/type.ts
index 8cb22aeb79..356c513fc3 100644
--- a/src/scopes/type.ts
+++ b/src/scopes/type.ts
@@ -105,9 +105,13 @@ export type AnonymousTypeName = `λ${string}`
 export const isAnonymousName = (name: string): name is AnonymousTypeName =>
     name[0] === "λ"
 
-export type asIn<t> = asIo<t, "in"> extends t ? t : asIo<t, "in">
+export type asIn<t> = [t, asIo<t, "out">] extends [asIo<t, "out">, t]
+    ? t
+    : asIo<t, "in">
 
-export type asOut<t> = asIo<t, "out"> extends t ? t : asIo<t, "out">
+export type asOut<t> = [t, asIo<t, "out">] extends [asIo<t, "out">, t]
+    ? t
+    : asIo<t, "out">
 
 type asIo<t, io extends "in" | "out"> = t extends ParsedMorph<infer i, infer o>
     ? io extends "in"