lix/doc/manual/rl-next/repl-doc-command.md

---
synopsis: Experimental REPL support for documentation comments using `:doc`
cls: 564
category: Features
credits: [Lunaphied, jade]
significance: significant
---

Using `:doc` in the REPL now supports showing documentation comments when defined on a function.

Previously this was only able to document builtins, however it now will show comments defined on a lambda as well.

This support is experimental and relies on an embedded version of [nix-doc](https://github.com/lf-/nix-doc).

The logic also supports limited Markdown formatting of doccomments and should easily support any [RFC 145](https://github.com/NixOS/rfcs/blob/master/rfcs/0145-doc-strings.md)
compatible documentation comments in addition to simple commented documentation.
repl: improve `:doc` builtin repl command to support lambdas. For a long time `nix repl` has supported displaying documentation set on builtins, however, it has long been convention to use Markdown comments on Nix functions themselves for documentation. This exposes that information to `nix repl` users in a nice and formatted way. NixOS/rfcs#145 doc-comments are primarily what this feature is intended to consume, however, support for lambda documentation in the repl is experimental. We do our best effort to support the RFC here. These changes are based on [the nix-doc library](https://github.com/lf-/nix-doc) and are licensed under the terms described in the relevant source files. Change-Id: Ic6fe947d39a22540705d890737e336c4720b0a22 2024-03-18 00:01:05 +00:00			`---`
			synopsis: Experimental REPL support for documentation comments using `:doc`
			`cls: 564`
doc: add release note credits and categories for all the changes in Lix This does not add missing release notes, and it doesn't do anything about the profiles feature we would really like to have so we can have consistent credit. Change-Id: I72a6f7acfcff85f380be17dac76501a6f4693776 2024-05-15 02:14:58 +00:00			`category: Features`
			`credits: [Lunaphied, jade]`
			`significance: significant`
repl: improve `:doc` builtin repl command to support lambdas. For a long time `nix repl` has supported displaying documentation set on builtins, however, it has long been convention to use Markdown comments on Nix functions themselves for documentation. This exposes that information to `nix repl` users in a nice and formatted way. NixOS/rfcs#145 doc-comments are primarily what this feature is intended to consume, however, support for lambda documentation in the repl is experimental. We do our best effort to support the RFC here. These changes are based on [the nix-doc library](https://github.com/lf-/nix-doc) and are licensed under the terms described in the relevant source files. Change-Id: Ic6fe947d39a22540705d890737e336c4720b0a22 2024-03-18 00:01:05 +00:00			`---`

			Using `:doc` in the REPL now supports showing documentation comments when defined on a function.

			`Previously this was only able to document builtins, however it now will show comments defined on a lambda as well.`

			`This support is experimental and relies on an embedded version of [nix-doc](https://github.com/lf-/nix-doc).`

			`The logic also supports limited Markdown formatting of doccomments and should easily support any [RFC 145](https://github.com/NixOS/rfcs/blob/master/rfcs/0145-doc-strings.md)`
			`compatible documentation comments in addition to simple commented documentation.`