fn: add conversions between Result and Option

fn/option_test.go

@@ -1,6 +1,8 @@
 package fn
 
 import (
+	"errors"
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -9,3 +11,18 @@ import (
 func TestOptionUnwrapOrFail(t *testing.T) {
 	require.Equal(t, Some(1).UnwrapOrFail(t), 1)
 }
+
+func TestSomeToOk(t *testing.T) {
+	err := errors.New("err")
+	require.Equal(t, Some(1).SomeToOk(err), Ok(1))
+	require.Equal(t, None[uint8]().SomeToOk(err), Err[uint8](err))
+}
+
+func TestSomeToOkf(t *testing.T) {
+	errStr := "err"
+	require.Equal(t, Some(1).SomeToOkf(errStr), Ok(1))
+	require.Equal(
+		t, None[uint8]().SomeToOkf(errStr),
+		Err[uint8](fmt.Errorf(errStr)),
+	)
+}