However, the standard workflow for an experimental feature is as follows:
- A new feature is implemented in a *pull request*
- It is guarded by an experimental feature flag that is disabled by default
- The pull request is merged, the *experimental* feature ends up in a release
- Using the feature requires explicitly enabling it, signifying awareness of the potential risks
- Being experimental, the feature can still be changed arbitrarily
- The feature can be *removed*
- The associated experimental feature flag is also removed
- The feature can be declared *stable*
- The associated experimental feature flag is removed
- There should be enough evidence of users having tried the feature, such as feedback, fixed bugs, demonstrations of how it is put to use
- Maintainers must feel confident that:
- The feature is designed and implemented sensibly, that it is fit for purpose
- Potential interactions are well-understood
- Stabilising the feature will not incur an outsized maintenance burden in the future
The following diagram illustrates the process:
```
.------.
| idea |
'------'
|
discussion, design, implementation
|
| .-------.
| | |
v v |
.--------------. review
| pull request | |
'--------------' |
| ^ | |
| | '-------'
.---' '----.
| |
merge user feedback,
| (breaking) changes
| |
'---. .----'
| |
v |
+--------------+
.---| experimental |----.
| +--------------+ |
| |
decision to stabilise decision against
| keeping the feature
| |
v v
+--------+ +---------+
| stable | | removed |
+--------+ +---------+
```
# Relation to the RFC process
Experimental features and [RFCs](https://github.com/NixOS/rfcs/) both allow approaching substantial changes while minimizing the risk.
However they serve different purposes:
- An experimental feature enables developers to iterate on and deliver a new idea without committing to it or requiring a costly long-running fork.
It is primarily an issue of *implementation*, targeting Nix developers and early testers.
- The goal of an RFC is to make explicit all the implications of a change:
Explain why it is wanted, which new use-cases it enables, which interface changes it requires, etc.
It is primarily an issue of *design* and *communication*, targeting the broader community.
This means that experimental features and RFCs are orthogonal mechanisms, and can be used independently or together as needed.
# Currently available experimental features
{{#include ./experimental-feature-descriptions.md}}