radn-rs/src/rstd/fallible.rs

36 lines
1.2 KiB
Rust

//! Shorthands for using [`Context::Fallible`].
use fail::*;
use crate::func::context::*;
use super::*;
/// Preferred monad for fallible uses.
pub type FallibleMonad<'a, Ctx, E> = <<Ctx as Context<'a>>::Fallible as MonadFailAny<'a>>::W<E>;
/// Preferred [Wrapped] [Result].
pub type FallibleWrapped<'a, Ctx, A, E> = Wrap<'a, A, FallibleMonad<'a, Ctx, E>>;
/// Extention trait for simpler conversion between [`FunctorContext::T`] and [`Context::Fallible`].
///
/// Until either Rust type system or [`crate::func`] take serious changes,
/// this is the preferred way to switch between [Wrapped] and [fallible].
pub trait FallibleContext<'a>: Context<'a> {
/// Convert a fallible wrapped into a wrapped result.
fn unstuff<A: 'a, E: 'a>(
wa: WrapE<'a, A, E, <Self as Context<'a>>::Fallible>,
) -> WrapC<'a, Result<A, E>, Self> {
Self::Fallible::unstuff(wa)
}
/// Convert a wrapped result into a fallible wrapped.
fn stuff<A: 'a, E: 'a>(
fa: WrapC<'a, Result<A, E>, Self>,
) -> WrapE<'a, A, E, <Self as Context<'a>>::Fallible> {
Self::Fallible::stuff(fa)
}
}
impl<'a, Ctx: Context<'a>> FallibleContext<'a> for Ctx {}