34 lines
570 B
Rust
34 lines
570 B
Rust
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use std::marker::PhantomData;
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pub trait StatefulFuture<S> {}
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pub struct Never<T>(PhantomData<T>);
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impl<T> StatefulFuture<T> for Never<T> {}
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pub struct RaceBuilder<F, S> {
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future: F,
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_phantom: PhantomData<S>,
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}
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impl<T, F> RaceBuilder<T, F>
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where
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F: StatefulFuture<Option<T>>,
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{
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pub fn when(self) {}
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}
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pub struct Race<T, R> {
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race: R,
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_phantom: PhantomData<T>,
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}
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impl<T, R> Race<T, R>
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where
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R: Fn(RaceBuilder<T, Never<T>>),
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{
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pub fn new(race: R) {}
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}
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fn main() {
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Race::new(|race| race.when()); //~ ERROR type annotations needed
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}
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