pipa-lang 1.0.0-alpha.1

A tiny template language
Documentation 
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// SPDX-FileCopyrightText: Copyright 2026 olav@occy.org
// SPDX-License-Identifier: MPL-2.0

use crate::lang::adapter::Adapter;
use crate::lang::arity::Arity;
use crate::lang::arity::assert_func_arity;
use crate::lang::error::Error;
use crate::lang::eval::eval_node;
use crate::lang::eval::keys_from_node;
use crate::lang::eval::record_setter;
use crate::lang::machine::Machine;
use crate::lang::node::Node;
use crate::value::Value;
use crate::value::span::Span;

pub(crate) fn set(
    adapter: &impl Adapter,
    machine: &mut Machine<'_>,
    stdin: Option<&Value>,
    node: Node,
) -> Result<Value, Error> {
    assert_func_arity(adapter, machine, stdin, &node, &Arity::min(2))?;

    let span = Span::from(&node);
    let nodes = node.into_list().unwrap_or_default();

    let Some(keys) = keys_from_node(adapter, machine, nodes[2].clone())? else {
        return Ok(Value::default());
    };

    let mut value = {
        let value = nodes.get(4..).unwrap_or_default();
        let value = Node::Pipe(Span::default(), value.to_vec());
        let value = eval_node(adapter, machine, stdin, value)?;
        value.or_else(|| stdin.cloned()).unwrap_or_default()
    };

    value.trace(span);
    record_setter(adapter, machine, &keys, value)?;

    Ok(Value::default())
}