treaty -


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use crate::{
    build::Builder,
    effect::{Effect, Future},
    Walker,
};

#[inline]
pub fn transform<
    'a,
    'ctx,
    B: Builder<'ctx, Effect = E> + 'a,
    W: Walker<'ctx, Effect = E> + 'a,
    E: Effect<'ctx>,
>(
    seed: B::Seed,
    walker: W,
) -> Future<'a, 'ctx, (Result<B::Value, B::Error>, Result<W::Output, W::Error>), E> {
    E::wrap(async {
        // Create builder from seed value;
        let mut builder = B::from_seed(seed).await;

        // Walk the walker with the builder as the visitor.
        let walker_result = walker.walk(builder.as_visitor()).await;

        // Finish building the value.
        let builder_result = builder.build().await;

        (builder_result, walker_result)
    })
}