corophage 0.4.0

Algebraic effects for stable Rust
Documentation 
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/// Fallback `yield_!` macro that produces a clear error when used outside
/// an `#[effectful]` function.
///
/// Inside an `#[effectful]` function, this macro is shadowed by a local
/// `macro_rules!` definition that expands to the correct yielder call.
#[macro_export]
macro_rules! yield_ {
    ($($tt:tt)*) => {
        ::core::compile_error!("yield_!() can only be used inside an #[effectful] function")
    };
}

/// Fallback `invoke!` macro that produces a clear error when used outside
/// an `#[effectful]` function.
///
/// Inside an `#[effectful]` function, this macro is shadowed by a local
/// `macro_rules!` definition that expands to the correct yielder call.
#[macro_export]
macro_rules! invoke {
    ($($tt:tt)*) => {
        ::core::compile_error!("invoke!() can only be used inside an #[effectful] function")
    };
}

/// Constructs a coproduct type from a list of [`Effect`](crate::Effect) types.
///
/// `Effects![A, B, C]` expands to `Coprod!(A, B, C)` from `frunk_core`.
///
/// Supports the `...Tail` spread syntax to splice in an existing effects type alias,
/// following the same convention as `Coprod!(...Tail)` from frunk:
///
/// ```ignore
/// type Base = Effects![Ask, Log];
/// type Extended = Effects![GetConfig, ...Base];
/// // Equivalent to: Effects![GetConfig, Ask, Log]
/// ```
///
/// The spread must appear as the last argument.
#[macro_export]
macro_rules! Effects {
    [] => {
        ::frunk_core::Coprod!()
    };
    [...$Rest:ty] => {
        $Rest
    };
    [$A:ty, $($tok:tt)*] => {
        ::frunk_core::coproduct::Coproduct<$A, $crate::Effects![$($tok)*]>
    };
    [$A:ty] => {
        $crate::Effects![$A,]
    };
}