libexpr: experimental pipe operators

doc/manual/rl-next/pipe-operators.md

@@ -0,0 +1,28 @@
+---
+synopsis: "Add `pipe-operators` experimental feature"
+prs:
+- 11131
+---
+
+This is a draft implementation of [RFC 0148](https://github.com/NixOS/rfcs/pull/148).
+
+The `pipe-operators` experimental feature adds [`<|` and `|>` operators][pipe operators] to the Nix language.
+*a* `|>` *b* is equivalent to the function application *b* *a*, and
+*a* `<|` *b* is equivalent to the function application *a* *b*.
+
+For example:
+
+```
+nix-repl> 1 |> builtins.add 2 |> builtins.mul 3
+9
+
+nix-repl> builtins.add 1 <| builtins.mul 2 <| 3
+7
+```
+
+`<|` and `|>` are right and left associative, respectively, and have lower precedence than any other operator.
+These properties may change in future releases.
+
+See [the RFC](https://github.com/NixOS/rfcs/pull/148) for more examples and rationale.
+
+[pipe operators]: @docroot@/language/operators.md#pipe-operators