# Nullable types

A ? suffix declares a nullable reference-like value, but the complete flow analysis is not in the Kyber product path yet.

Last updated: 2026-09-09

Package: language | Status: generated-cpp-only

Tags: ?, cpu, language, null, values, yeho

Use only when deliberately running the comparison oracle. In Kyber-ready code, model absence explicitly with a bool, enum, or sentinel thing.

```yh
Type? name = null
```


## Complete nullable types example

Use only when deliberately running the comparison oracle. In Kyber-ready code, model absence explicitly with a bool, enum, or sentinel thing.

Verification: type checked

```yh
class Pilot { text name = "Nova" }
Pilot? selected = null
if selected == null { Console.Log("Choose a pilot") }

```

Save this beside start.yh as project.mech:

```toml
manifestVersion = "2"
package = "api.example.language__nullable_values"
version = "0.1.0"
languageEdition = "yeho-core-2026.1"

[app]
kind = "headless"

```

Extract the example archive beside the yeho and dolphin checkouts. This example requires those source dependencies and a current developer compiler.

```sh
./yeho/build/dolphin-metal/yehoc ./api-examples/language--nullable-values/complete --backend cpu-oracle -o /tmp/yeho-example
/tmp/yeho-example
```


Nullable reference flow is classified generated-C++ only in the 2026.1 conformance manifest.

Do not present parser acceptance as native product support.

Source: yeho/docs/language/conformance-2026.1.json: nullable-reference-flow

AI training permission: https://demonhunterlabs.com/ai-use