maybe?

coderd/util/maybe/maybe.go

@@ -0,0 +1,42 @@
+// Package maybe contains utility functions for an Optional data type.
+package maybe
+
+// Maybe is a generic type that holds a pointer to a value of type T
+// and an error. Either *T will be nil, or error will be nil.
+type Maybe[T any] struct {
+	val *T
+	err error
+}
+
+// Valid() returns true if Maybe contains a value of type *T.
+func (m *Maybe[T]) Valid() bool {
+	return m.err == nil && m.val != nil
+}
+
+// Error() returns the error contained in Maybe.
+func (m *Maybe[T]) Error() error {
+	return m.err
+}
+
+// Value() returns the value contained in Maybe.
+func (m *Maybe[T]) Value() *T {
+	return m.val
+}
+
+// Of is a function that takes a value of type T and returns
+// a valid Maybe holding a pointer to that value.
+func Of[T any](v T) *Maybe[T] {
+	return &Maybe[T]{
+		val: &v,
+		err: nil,
+	}
+}
+
+// Not is a function that returns an invalid Maybe that
+// only contains the given error.
+func Not[T any](err error) *Maybe[T] {
+	return &Maybe[T]{
+		val: nil,
+		err: err,
+	}
+}

coderd/util/maybe/maybe_test.go

@@ -0,0 +1,26 @@
+package maybe_test
+
+import (
+	"fmt"
+
+	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/v2/coderd/util/maybe"
+)
+
+func ExampleMaybe() {
+	m1 := maybe.Of("hello")
+	m2 := maybe.Not[string](xerrors.New("goodbye"))
+	_, _ = fmt.Println(m1.Valid())
+	_, _ = fmt.Println(*m1.Value())
+	_, _ = fmt.Println(m1.Error())
+	_, _ = fmt.Println(m2.Valid())
+	_, _ = fmt.Println(m2.Value())
+	_, _ = fmt.Println(m2.Error())
+	// Output: true
+	// hello
+	// <nil>
+	// false
+	// <nil>
+	// goodbye
+}