resultra v0.1.4
Resultra
Rust inspired result structure for javascript
Example
import { ok, err } from 'resultra'
import { parseInt } from 'reusltra/utils'
function parseName() {
const name = prompt('Enter your name');
return name
? ok(name)
: err(new Error('name is required'))
}
function parseAge() {
const age = prompt('Enter your age');
return age ? parseInt(age, 10) : err(new Error('Age is required'))
}
const personResult = parseName()
.andThen(name =>
parseAge()
.map(age =>
({ name, age })
)
);
if (personResult.ok()) {
const person = personResult.unwrap();
console.log('Hello', person.name)
console.log('You are', person.age, 'years old')
} else {
console.log('Error:', personResult.error)
}Constructors
ok
Creates an OkResult
const okResult = ok(1);
const okValue = okResult.valueerr
Creates an ErrResult
const errResult = err('error');
const errValue = errResult.errorMethods
ok
Returns true if the result is an OkResult
Example:
map
Maps the value of the result if it is an OkResult
andThen
Maps the value of the result to another result if it is an OkResult
unwrap
Unwraps the value of the result if it is an OkResult. Throws an error if the result is an ErrResult.
Utils
catchError
Catches errors thrown by a function and returns a Result
const result = catchError(() => {
throw new Error('error')
})
assert(!result.ok(), 'result should be an error here')
assert(result.error.message === 'error')catchAsync
Catches errors thrown by an async function and returns a Promise of a Result
const result = await catchAsync(async () => {
throw new Error('error')
})
assert(!result.ok(), 'result should be an error here')
assert(result.error.message === 'error')collect
Collects an array of results into a single result of all the values. If any of the results are errors, the first error is returned.
const results = collect([
ok(1),
ok(2),
ok(3),
])
assert(results.ok(), 'results should be ok')
assert(results.value.length === 3, 'results should have 3 values')const results = collect([
ok(1),
err('error'),
ok(3),
])
assert(!results.ok(), 'results should be an error')
assert(results.error === 'error', 'error should be "error"')collectAsync
Collects an array of async results into a single result of all the values. If any of the results are errors, the first error is returned.
const results = await collectAsync([
Promise.resolve(ok(1)),
Promise.resolve(ok(2)),
Promise.resolve(ok(3)),
])
assert(results.ok(), 'results should be ok')
assert(results.value.length === 3, 'results should have 3 values')const results = await collectAsync([
Promise.resolve(ok(1)),
Promise.resolve(err('error')),
Promise.resolve(ok(3)),
])
assert(!results.ok(), 'results should be an error')
assert(results.error === 'error', 'error should be "error"')successes
Collects an array of results into an array of all successful result values.
const results = successes([
ok(1),
ok(2),
ok(3),
])
assert(results.length === 3, 'results should have 3 values')const results = successes([
ok(1),
err('error'),
ok(3),
])
assert(results.length === 2, 'results should be equal to [1,3]')successesAsync
Collects an array of async results into an array of all successful result values.
const results = await successesAsync([
Promise.resolve(ok(1)),
Promise.resolve(ok(2)),
Promise.resolve(ok(3)),
])
assert(results.length === 3, 'results should have 3 values')const results = await successesAsync([
Promise.resolve(ok(1)),
Promise.resolve(err('error')),
Promise.reject(ok(3)),
])
assert(results.length === 1, 'results should be equal to [1]')fromJsonRpc
Creates a Result from a JSON RPC response
const result = fromJsonRpc({
result: 1,
})
assert(result.ok(), 'result should be ok')
assert(result.value === 1, 'result should be equal to 1')const result = fromJsonRpc({
error: new Error('error'),
})
assert(!result.ok(), 'result should be an error')
assert(result.error.message === 'error', 'error should be "error"')fromPromise
Creates a Promise of Result from a Promise. It will be ok, if the promise resolves, or an error, if the promise rejects.
const result = await fromPromise(Promise.resolve(1))
assert(result.ok(), 'result should be ok')
assert(result.value === 1, 'result should be equal to 1')const result = await fromPromise(Promise.reject(new Error('error')))
assert(!result.ok(), 'result should be an error')
assert(result.error.message === 'error', 'error should be "error"')parseInt
Creates a Result of number from a string and a base. It will be ok, if the string can be parsed, or an error, if the string cannot be parsed.
const result = parseInt('1', 10)
assert(result.ok(), 'result should be ok')
assert(result.value === 1, 'result should be equal to 1')const result = parseInt('a', 10)
assert(!result.ok(), 'result should be an error')
assert(result.error.message === 'Failed to parse a as number', 'error should be "Failed to parse a as number"')parseFloat
Creates a Result of number from a string. It will be ok, if the string can be parsed, or an error, if the string cannot be parsed.
const result = parseFloat('1.1')
assert(result.ok(), 'result should be ok')
assert(result.value === 1.1, 'result should be equal to 1.1')const result = parseFloat('a')
assert(!result.ok(), 'result should be an error')
assert(result.error.message === 'Failed to parse a as number', 'error should be "Failed to parse a as number"')assert
Returns ok result if value is truthy, err with specified message if not
const result = assert(1, 'error')
assert(result.ok(), 'result should be ok')
assert(result.value === 1, 'result should be equal to 1')const result = assert(0, 'error')
assert(!result.ok(), 'result should be an error')
assert(result.error.message === 'error', 'error should be "error"')validate
Checks if predicate returns true for a value, returns ok result if true, err with specified message if not
const result = validate(1, (value) => value === 1, 'error')
assert(result.ok(), 'result should be ok')
assert(result.value === 1, 'result should be equal to 1')const result = validate(0, (value) => value === 1, 'error')
assert(!result.ok(), 'result should be an error')
assert(result.error.message === 'error', 'error should be "error"')