Module primop 

Nix primitive operations (primops).

This module provides a safe, closure-based API for registering custom Nix primitive operations (primops).

Overview

Primops are Rust functions that appear as Nix builtins. There are two ways to expose a primop:

• Global builtin: call PrimOp::register before creating any EvalState. All subsequently created states will include the primop in builtins.
• Value-embedded: call PrimOp::into_value on an existing EvalState to obtain a callable Value.

Example

use std::sync::Arc;

use nix_bindings::{
  Context,
  EvalStateBuilder,
  Store,
  primop::{NixValueOps, PrimOp},
};

let ctx = Arc::new(Context::new()?);

// Register a global builtin that doubles an integer
PrimOp::new(&ctx, "double", 1, Some("Double an integer"), |args, ret| {
  let n = args[0].as_int()?;
  ret.set_int(n * 2)
})?
.register(&ctx)?;

let store = Arc::new(Store::open(&ctx, None)?);
let state = EvalStateBuilder::new(&store)?.build()?;
let result = state.eval_from_string("builtins.double 21", "<eval>")?;
assert_eq!(result.as_int()?, 42);

Structs

ArgAttrs

A borrowed Nix attribute set value.

ArgList

A borrowed Nix list value.

PrimOp

A Nix primitive operation (primop) wrapping a Rust closure.

PrimOpArg

A borrowed Nix value passed as an argument to a primop callback.

PrimOpRet

The writable return-value slot provided to a primop closure.

PrimOpValue

An owned Nix value used within a primop callback.

Traits

NixValueOps

Read access to a Nix value.