add new funky type

lib/funky/funky.go

@@ -29,3 +29,40 @@ func (m *maybe[V]) IsNothing() bool {
 func (m *maybe[V]) Value() V {
 	return m.value
 }
+
+// Either
+
+type Either[V any] interface {
+	Ok() bool
+	Right() V
+	Left() error
+}
+
+type either[V any] struct {
+	ok    bool
+	right V
+	left  error
+}
+
+func Right[V any](v V) Either[V] {
+	return &either[V]{
+		ok:    true,
+		right: v,
+	}
+}
+
+func Left[V any](e error) Either[V] {
+	return &either[V]{left: e}
+}
+
+func (et *either[V]) Ok() bool {
+	return et.ok
+}
+
+func (et *either[V]) Right() V {
+	return et.right
+}
+
+func (et *either[V]) Left() error {
+	return et.left
+}

tests/funky_test.go

@@ -1,6 +1,7 @@
 package scopes_test
 
 import (
+	"fmt"
 	tbase "testing"
 
 	"git.sr.ht/~cco/go-scopes/lib/funky"
@@ -10,6 +11,7 @@ import (
 func TestFunky(tb *tbase.T) {
 	t := testing.SetUp(tb)
 	t.Run("maybe", MaybeTest)
+	t.Run("either", EitherTest)
 	t.Run("iterator", IteratorTest)
 }
 
@@ -21,6 +23,15 @@ func MaybeTest(t *testing.T) {
 	t.AssertEqual(i1.Value(), 3)
 }
 
+func EitherTest(t *testing.T) {
+	var e0 funky.Either[int] = funky.Right[int](7)
+	t.AssertEqual(e0.Ok(), true)
+	t.AssertEqual(e0.Right(), 7)
+	var e1 funky.Either[int] = funky.Left[int](fmt.Errorf("Some Error"))
+	t.AssertEqual(e1.Ok(), false)
+	t.AssertEqual(fmt.Sprint(e1.Left()), "Some Error")
+}
+
 func IteratorTest(t *testing.T) {
 	sl := []int{3, 4, 5}
 	var it funky.Iterator[int] = funky.SliceIterator[int](sl)