add generic functional stuff: Maybe

lib/funky/funky.go

@@ -0,0 +1,27 @@
+package funky
+
+type Maybe[V any] interface {
+	IsNothing() bool
+	Value() V
+}
+
+type maybe[V any] struct {
+	isNothing bool
+	value     V
+}
+
+func Nothing[V any]() Maybe[V] {
+	return &maybe[V]{isNothing: true}
+}
+
+func Just[V any](v V) Maybe[V] {
+	return &maybe[V]{false, v}
+}
+
+func (m *maybe[V]) IsNothing() bool {
+	return m.isNothing
+}
+
+func (m *maybe[V]) Value() V {
+	return m.value
+}

tests/funky_test.go

@@ -0,0 +1,21 @@
+package scopes_test
+
+import (
+	tbase "testing"
+
+	"git.sr.ht/~cco/go-scopes/lib/funky"
+	"git.sr.ht/~cco/go-scopes/testing"
+)
+
+func TestFunky(tb *tbase.T) {
+	t := testing.SetUp(tb)
+	t.Run("maybe", MaybeTest)
+}
+
+func MaybeTest(t *testing.T) {
+	var i0 funky.Maybe[int] = funky.Nothing[int]()
+	t.AssertEqual(i0.IsNothing(), true)
+	var i1 funky.Maybe[int] = funky.Just(3)
+	t.AssertEqual(i1.IsNothing(), false)
+	t.AssertEqual(i1.Value(), 3)
+}