Crate promisery 

Promises for Rust

This crate provides a JavaScript-inspired, ergonomic, and composable Promise type for Rust, supporting background work, chaining, and error handling with Result.

Features

• ECMAScript 5-style promises with Rust’s type safety
• Chaining with .then, .map, and .map_err
• Combinators: Promise::all, Promise::race
• Panic-safe: panics in promise tasks are detected and reported
• Fully documented with tested examples
• Timeout and deadline support: Use Promise::wait_timeout, Promise::wait_deadline to wait with timeouts or deadlines.
• Safe and unsafe waiting: Use Promise::wait for panic-safe waiting, or Promise::wait_nopanic for unsafe, panic-propagating waiting.

Example

use promisery::Promise;
let p = Promise::<_, ()>::new(|| Ok(2))
    .then(|res| res.map(|v| v * 10))
    .then(|res| res.map(|v| v + 5));
assert_eq!(p.wait(), Ok(Ok(25)));

Error Handling

All errors are handled via Result<T, E>. Panics in promise tasks are reported via PromisePanic (see Promise::wait).

Waiting for Results

• Use Promise::wait for panic-safe waiting (returns a double Result).
• Use Promise::wait_nopanic (unsafe) to panic if the background task panicked.
• Use Promise::wait_timeout or Promise::wait_deadline to wait with a timeout or until a deadline.

See Also

• Promise for the main type
• PromisePanic for panic detection
• Promise::wait, Promise::wait_nopanic, Promise::wait_timeout, Promise::wait_deadline for waiting options
• README.md for more details and usage

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Released under the MIT License.

Structs

Promise

A promise is a way of doing work in the background, similar to JavaScript promises.

PromisePanic

Error type returned when a promise panics during execution.

Enums

WaitTimeoutError

Error type returned when waiting on a promise with a timeout.