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//! Higher-kinded types for Rust standard library types.
//!
//! This module provides the type cosntructors needed to use the types
//! in the Rust standard library in a higher-kinded way.

use super::{Kind1, Kind2, K2P1_1, K2P1_2};

/// An `Option<*>` type constructor.
///
/// The `Option<*>` type constructor has kind `* -> *`.
pub struct OptionC;

impl<T> Kind1<T> for OptionC {
    type Inner = Option<T>;
}

/// A `Vec<*>` type constructor.
///
/// The `Vec<*>` type constructor has kind `* -> *`.
pub struct VecC;

impl<T> Kind1<T> for VecC {
    type Inner = Vec<T>;
}

/// A `Result<*, *>` type constructor.
///
/// The `Result<*, *>` type constructor has kind `* -> * -> *`.
pub struct ResultC;

impl<T, E> Kind2<T, E> for ResultC {
    type Inner = Result<T, E>;
}

/// A `Result<T, *>` type constructor.
///
/// The `Result<T, *>` type constructor has kind `* -> *`.
pub type ResultLeft<T> = K2P1_1<ResultC, T>;

/// A `Result<*, T>` type constructor.
///
/// The `Result<*, T>` type constructor has kind `* -> *`.
pub type ResultRight<T> = K2P1_2<ResultC, T>;

/// A `(*, *)` type constructor.
///
/// The `(*, *)` type constructor has kind `* -> * -> *`.
pub struct PairC;

impl<T, U> Kind2<T, U> for PairC {
    type Inner = (T, U);
}

/// A `(T, *)` type constructor.
///
/// The `(T, *)` type constructor has kind `* -> *`.
pub type PairLeft<T> = K2P1_1<PairC, T>;

/// A `(*, T)` type constructor.
///
/// The `(*, T)` type constructor has kind `* -> *`.
pub type PairRight<T> = K2P1_2<PairC, T>;