A Task
which resolves to the resolution value of the promise or
rejects with the rejection value of the promise or any error thrown while
invoking fn
.
Given a function which takes no arguments and returns a Promise
and a
function which accepts an unknown
rejection reason and transforms it into a
known rejection type E
, return a Task<T, E>
for the result
of invoking that function. This safely handles functions which fail
synchronously or asynchronously, so unlike fromPromise
is safe to
use with values which may throw errors before producing a Promise
.
import { safelyTryOrElse } from 'true-myth/task';
function throws(): Promise<number> {
throw new Error("Uh oh!");
}
// Note: passing the function by name, *not* calling it.
let theTask = safelyTryOr(
(reason) => `Something went wrong: ${reason}`,
throws
);
let theResult = await theTask;
console.log(theResult.toString); // Err("Something went wrong: Error: Uh oh!")
You can also write this in “curried” form, passing just the fallback value and getting back a function which accepts the:
import { safelyTryOr } from 'true-myth/task';
function throws(): Promise<number> {
throw new Error("Uh oh!");
}
// Note: passing the function by name, *not* calling it.
let withFallback = safelyTryOrElse<number, string>(
(reason) => `Something went wrong: ${reason}`
);
let theResult = await withFallback(throws);
console.log(theResult.toString); // Err("Something went wrong: Error: Uh oh!")
Note that in the curried form, you must specify the expected T
type of the
resulting Task
, or else it will always be unknown
.
The function to use to transform the rejectionr easons if the
Promise
produced by fn
rejects.
A Task
which resolves to the resolution value of the promise or
rejects with the rejection value of the promise or any error thrown while
invoking fn
.
Given a function which takes no arguments and returns a
Promise
and a function which accepts anunknown
rejection reason and transforms it into a known rejection typeE
, return aTask<T, E>
for the result of invoking that function. This safely handles functions which fail synchronously or asynchronously, so unlikefromPromise
is safe to use with values which may throw errors before producing aPromise
.Examples
You can also write this in “curried” form, passing just the fallback value and getting back a function which accepts the:
Note that in the curried form, you must specify the expected
T
type of the resultingTask
, or else it will always beunknown
.