nushell/crates/nu-command/src/core_commands/module.rs

use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{Category, PipelineData, Signature, SyntaxShape};

#[derive(Clone)]
pub struct Module;

impl Command for Module {
    fn name(&self) -> &str {
        "module"
    }

    fn usage(&self) -> &str {
        "Define a custom module"
    }

    fn signature(&self) -> nu_protocol::Signature {
        Signature::build("module")
            .required("module_name", SyntaxShape::String, "module name")
            .required(
                "block",
                SyntaxShape::Block(Some(vec![])),
                "body of the module",
            )
            .category(Category::Core)
    }

    fn run(
        &self,
        _engine_state: &EngineState,
        _stack: &mut Stack,
        call: &Call,
        _input: PipelineData,
    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
        Ok(PipelineData::new(call.head))
    }
}