1 files changed, 32 insertions, 0 deletions
diff --git a/test/typeparam/fact.go b/test/typeparam/fact.go
new file mode 100644
index 0000000..3c9a13a
--- /dev/null
+++ b/test/typeparam/fact.go
@@ -0,0 +1,32 @@
+// run
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "fmt"
+
+func fact[T interface{ ~int | ~int64 | ~float64 }](n T) T {
+	if n == 1 {
+		return 1
+	}
+	return n * fact(n-1)
+}
+
+func main() {
+	const want = 120
+
+	if got := fact(5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := fact[int64](5); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	if got := fact(5.0); got != want {
+		panic(fmt.Sprintf("got %f, want %f", got, want))
+	}
+}