1 files changed, 83 insertions, 0 deletions
diff --git a/src/go/parser/testdata/linalg.go2 b/src/go/parser/testdata/linalg.go2
new file mode 100644
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--- /dev/null
+++ b/src/go/parser/testdata/linalg.go2
@@ -0,0 +1,83 @@
+// Copyright 2019 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 linalg
+
+import "math"
+
+// Numeric is type bound that matches any numeric type.
+// It would likely be in a constraints package in the standard library.
+type Numeric interface {
+	type int, int8, int16, int32, int64,
+		uint, uint8, uint16, uint32, uint64, uintptr,
+		float32, float64,
+		complex64, complex128
+}
+
+func DotProduct[T Numeric](s1, s2 []T) T {
+	if len(s1) != len(s2) {
+		panic("DotProduct: slices of unequal length")
+	}
+	var r T
+	for i := range s1 {
+		r += s1[i] * s2[i]
+	}
+	return r
+}
+
+// NumericAbs matches numeric types with an Abs method.
+type NumericAbs[T any] interface {
+	Numeric
+
+	Abs() T
+}
+
+// AbsDifference computes the absolute value of the difference of
+// a and b, where the absolute value is determined by the Abs method.
+func AbsDifference[T NumericAbs](a, b T) T {
+	d := a - b
+	return d.Abs()
+}
+
+// OrderedNumeric is a type bound that matches numeric types that support the < operator.
+type OrderedNumeric interface {
+	type int, int8, int16, int32, int64,
+		uint, uint8, uint16, uint32, uint64, uintptr,
+		float32, float64
+}
+
+// Complex is a type bound that matches the two complex types, which do not have a < operator.
+type Complex interface {
+	type complex64, complex128
+}
+
+// OrderedAbs is a helper type that defines an Abs method for
+// ordered numeric types.
+type OrderedAbs[T OrderedNumeric] T
+
+func (a OrderedAbs[T]) Abs() OrderedAbs[T] {
+	if a < 0 {
+		return -a
+	}
+	return a
+}
+
+// ComplexAbs is a helper type that defines an Abs method for
+// complex types.
+type ComplexAbs[T Complex] T
+
+func (a ComplexAbs[T]) Abs() ComplexAbs[T] {
+	r := float64(real(a))
+	i := float64(imag(a))
+	d := math.Sqrt(r * r + i * i)
+	return ComplexAbs[T](complex(d, 0))
+}
+
+func OrderedAbsDifference[T OrderedNumeric](a, b T) T {
+	return T(AbsDifference(OrderedAbs[T](a), OrderedAbs[T](b)))
+}
+
+func ComplexAbsDifference[T Complex](a, b T) T {
+	return T(AbsDifference(ComplexAbs[T](a), ComplexAbs[T](b)))
+}