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::args::eval_args;
use crate::lang::arity::Arity;
use crate::lang::arity::assert_func_arity;
use crate::lang::error::Error;
use crate::lang::machine::Machine;
use crate::lang::node::Node;
use crate::value::Value;
use crate::value::list::List;
use crate::value::map::Map;

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

    let mut args = eval_args(adapter, machine, stdin, node)?;
    let value = args.pop().flatten().unwrap_or_default();
    let keys = args.pop().flatten().unwrap_or_default().into_list();

    Ok(match value {
        Value::Bytes(_) => Value::default(),
        Value::List(v) => v
            .into_iter()
            .enumerate()
            .filter(|(i, _)| keys.contains(&Value::from(*i)))
            .map(|(_, v)| v)
            .collect::<List>()
            .into(),
        Value::Map(v) => v
            .into_iter()
            .filter(|(k, _)| keys.contains(&Value::from(k.clone())))
            .collect::<Map>()
            .into(),
    })
}