# Deliberately unavailable language features

Yeho Core 2026.1 explicitly does not admit generics, slices, interpolation, alternate numeric literals, compound assignment, computed properties, operator overloading, truthiness, or raw allocation/free.

Last updated: 2026-09-09

Package: language | Status: unavailable

Tags: +=, boundaries, cpu, free, generics, interpolation, language, malloc, operator, slices, yeho

Use the simple supported forms shown here. Treat a compiler rejection as a boundary, not an invitation to advertise unfinished syntax.

```yh
Generic algorithm -> concrete function or named thing
Slice/view -> list, buffer, start + count
Interpolation -> Text.Format
value += 1 -> value = value + 1
Computed property -> method
Truthiness -> explicit bool condition
Allocation/free -> owned value or runtime resource API
```


## Complete program

A complete example you can paste into start.yh.

Verification: type checked

```yh
// assert is not admitted; validate explicitly.
int score = 10
if score < 0 { Console.Error("Score must be nonnegative") }
else { Console.Log(Text.From(score)) }

```

Save this beside start.yh as project.mech:

```toml
manifestVersion = "2"
package = "api.example.language__unavailable_syntax"
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--unavailable-syntax/complete --backend cpu-oracle -o /tmp/yeho-example
/tmp/yeho-example
```


Unavailable means no stable or experimental product contract exists.

The exact list is machine-readable in the conformance manifest.

Source: yeho/docs/language/conformance-2026.1.json unavailable classifications

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