0055-hard-union-to-intersection

Author: coderhyy

type-challenges/0055-hard-union-to-intersection/template.ts

@@ -0,0 +1,6 @@
+// 参考 https://github.com/type-challenges/type-challenges/issues/1051
+type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (
+  arg: infer I
+) => void
+  ? I
+  : never;

type-challenges/0055-hard-union-to-intersection/test-cases.ts

@@ -0,0 +1,11 @@
+import type { Equal, Expect } from "@type-challenges/utils";
+
+type cases = [
+  Expect<Equal<UnionToIntersection<"foo" | 42 | true>, "foo" & 42 & true>>,
+  Expect<
+    Equal<
+      UnionToIntersection<(() => "foo") | ((i: 42) => true)>,
+      (() => "foo") & ((i: 42) => true)
+    >
+  >
+];