Rust-style error handling with context-aware errors, a result builder, bind() short-circuiting, bail/ensure helpers, typed/untyped errors, rich contextual propagation, and converts existing Result values for seamless interop.
Rust-style error handling for Kotlin.
AnyhowKt is a Kotlin Multiplatform (KMP) library inspired by Rust's
anyhow crate. It provides a simple, powerful,
and expressive way to handle errors with:
bind() (Rust ?-like behavior)bail, ensure, and structured error propagationsourceSets {
commonMain.dependencies {
implementation("io.github.itsvks19:anyhowkt:<version>")
}
}
dependencies {
implementation("io.github.itsvks19:anyhowkt:<version>")
}
val result = anyhow {
val a = parseInt("10").bind()
val b = parseInt("20").bind()
a + b
}
val value: Int = result.unwrap()
? Equivalent in KotlinRust:
let value = compute()?;
Kotlin (AnyhowKt):
val value = compute().bind()
This works inside anyhow { } blocks.
val result = anyhow {
val file = readFile("config.json")
.anyhowResult { "file not found" }
.bind() // Early return on readFile failure
parseConfig(file)
.anyhow()
.bind()
}.context("Failed to load application config")
Error output becomes:
Failed to load application config
Caused by: file not found
...
bail – Early Exitval result = anyhow {
if (user == null) {
bail("User not found")
}
user.name
}
ensure Helpersanyhow {
ensure(x > 0) { "x must be positive" }
ensureNotNull(user) { "user is required" }
ensureEquals(a, b) { "values must match" }
}
val kResult: Result<Int> = runCatching { riskyCall() }
val result: AnyhowResult<Int> = kResult.anyhow()
This library internally uses arrow-kt.
If you are using an IntelliJ IDEA or any other IDE from JetBrains, we strongly recommend installing the Arrow plug-in. The plug-in helps fix common problems, especially in the realm of typed errors and suggests more idiomatic alternatives when available.
MIT License.
PRs and feature requests are welcome! If you'd like to help add:
feel free to contribute ✨
anyhow { } result builderbind() for early-return error propagation (Rust ?).context() and withContext() for rich error messagesbail() for immediate failureensure() / ensureNotNull() helpersResult to AnyhowResultRust (anyhow) | Kotlin (AnyhowKt) |
|---|
anyhow::Result<T> | AnyhowResult<T> |
? | .bind() |
bail!("msg") | bail("msg") |
.context("msg") | .context("msg") |
ensure!(cond) | ensure(cond) |
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