# ?

Allow a reference type to also hold null.

Last updated: 2026-09-09

Package: language.operators | Status: documented

Tags: cpu, language, operator, type, yeho

A focused reference with a complete example. Numeric widths and experimental types still depend on the selected backend.

```yh
?
```


## 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/operator--symbol-8a8de8/complete --backend cpu-oracle -o /tmp/yeho-example
/tmp/yeho-example
```




Source: demonhunterlabs/app/lib/yeho-language-reference.ts

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