Some wrapper around values/function calls for distinguishing between values and errors in typescript with a discriminator type. If ok is true then we got a value, but if ok is false we got an error, simple enough.
Result from a synchronous function call
import { Res, type Result } from "@jmnuf/results";
const result: Result<number> = Res.syncCall(() => {
// Some code that may error
const num = Math.random();
if (num > 0.5) {
throw new Error("Number is too big");
}
return num;
});
if (result.ok) {
console.log(result.value); // value exists as a number here
} else {
console.error(result.error); // error exists as an Error instance
}
Result from an asynchronous function call
import { Res, type Result } from "@jmnuf/results";
async function myAsyncOperation() {
/*
* do some async operation that may throw an error
*/
}
async function myAsyncFn() {
const result = Res.asyncCall(() => myAsyncOperation());
if (result.ok) {
console.log("Operation succesful");
} else {
console.log("Operation failed");
}
}
Writing your own resulting function
import { Res, type Result } from "@jmnuf/results";
function myResultingFn() {
const value = Math.floor(Math.random() * 100);
if (value < 70) {
return Res.Err("Percentage is too low");
}
return Res.Ok(value);
}
const result = myResultingFn();
if (result.ok) {
console.log("Passing with a score of", result.value); // Result value is now a number
} else {
console.log("Failing score");
}