ksl 0.1.30

KSL core library and interpreter
Documentation 
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//! # ksl::builtin::write
//!
//! Built-in function `Write`.

use crate::{Environment, FALSE_SYMBOL, TRUE_SYMBOL, eval::apply::eval_apply, expand_tilde, value::Value};

pub(crate) fn builtin(args: &[Value], env: Environment) -> Result<Value, std::sync::Arc<str>> {
    if let [path, is_append, content] = args {
        match (
            eval_apply(path, env.clone())?,
            eval_apply(is_append, env.clone())?,
            eval_apply(content, env)?,
        ) {
            (Value::String(file_path), p @ Value::Atom(_), Value::String(text)) if p == *TRUE_SYMBOL || p == *FALSE_SYMBOL => {
                expand_tilde(file_path).and_then(|real_path| {
                    match std::fs::File::options()
                        .truncate(p == *FALSE_SYMBOL)
                        .append(p == *TRUE_SYMBOL)
                        .write(true)
                        .create(true)
                        .open(&real_path)
                        .and_then(|f| {
                            std::io::Write::write_all(
                                &mut std::io::BufWriter::new(f),
                                &text.bytes().collect::<Vec<u8>>(),
                            )
                        }) {
                        Ok(()) => Ok(Value::Unit),
                        Err(e) => Err(std::sync::Arc::from(format!(
                            concat!(
                                "Error[ksl::builtin::Write]: ",
                                "Write to file `{}` failed with `{}`."
                            ),
                            real_path.display(),
                            e
                        ))),
                    }
                })
            }
            (Value::String(_), Value::Atom(p), Value::String(_)) => Err(std::sync::Arc::from(format!(
                concat!("Error[ksl::builtin::Write]: ", "`#{}` is not a boolean"),
                p
            ))),
            (Value::String(_), Value::Atom(_), e) => Err(std::sync::Arc::from(format!(
                concat!(
                    "Error[ksl::builtin::Write]: ",
                    "Expect a string, but got: `{}`."
                ),
                e
            ))),
            (Value::String(_), e, _) => Err(std::sync::Arc::from(format!(
                concat!("Error[ksl::builtin::Write]: ", "Unexpected value: `{}`."),
                e
            ))),
            (e, _, _) => Err(std::sync::Arc::from(format!(
                concat!("Error[ksl::builtin::Write]: ", "Unexpected value: `{}`."),
                e
            ))),
        }
    } else {
        Err(std::sync::Arc::from(format!(
            concat!(
                "Error[ksl::builtin::Write]: ",
                "Expected 3 parameters, but {} were passed."
            ),
            args.len()
        )))
    }
}