Typescript errors as values
This library takes heavy inspiration from Rust's Either, Option, and Result types.
npm i teav --save
Documentation is available at https://jdeurt.github.io/teav.
Javascript errors are invisible to Typescript's type system. To solve this, you
can use the Result type to clearly indicate when a function may fail.
import { Result } from "teav";
function tryToMultiply(x: number, y: number): Result<number, Error> {
if (x < 10 && y < 10) {
return Result.Ok(x * y);
}
return Result.Err(new Error("Cannot multiply! Numbers are too big!"));
}
const z = tryToMultiply(10, 11);
if (z.isOk()) {
console.log("Result: " + z.unwrap());
} else {
console.log("Uh oh!");
}Teav supports automatically converting the result of a function call to a Result.
import { Result } from "teav";
import { myIoOperationSync } from "./my/io/utils";
// `result` will be `Err` if `myIoOperation` throws an error.
const result = Result.unsafeFrom(() => myIoOperationSync());
// `mapOrElse` is just one of the many ways of handling `Result` objects.
const data = result.mapOrElse(
(error) => {
// Handle error case.
},
(data) => {
// Handle data.
}
);You can also be more explicit about what errors are expected for an additional layer of safety.
import { Result } from "teav";
import { myIoOperationSync, IoError } from "./my/io/utils";
// If `myIoOperationSync` throws an error that is not an instance of IoError,
// that error will be rethrown.
const result = Result.from([IoError], () => myIoOperationSync());
// ...It also works with async functions.
import { Result } from "teav";
import { myIoOperation } from "./my/io/utils";
const result = await Result.unsafeFromAsync(() => myIoOperation());
const data = result.mapOrElse(
(error) => {
// Handle error case.
},
(data) => {
// Handle data.
}
);
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