@orodio/maybe


$3

``
yarn add @orodio/maybe
`

$3

`
import {
Just,
Nothing,
isJust,
isNothing,
bind,
scope,
} from "@orodio/maybe"

const isNumber = value =>
typeof value === 'number'
? Just(value)
: Nothing()

const isGreaterThanOrEqualTo = n => value =>
value >= n
? Just(value)
: Nothing()

const isLessThanOrEqualTo = n => value =>
value <= n
? Just(value)
: Nothing()

const inRange = (min, max) =>
bind([
isNumber,
isGreaterThanOrEqualTo(min),
isLessThanOrEqualTo(max),
])

const inc = d => value =>
Just(value + d)

const m1 = inRange(5, 10)(7)
assert(m1.value, 7)
assert(m1.toBoolean(), true)
assert(isJust(m1), true)
assert(isNothing(m1), false)

const m2 = inRange(5, 10)(15)
assert(m2.value, undefined)
assert(m2.toBoolean(), false)
assert(isJust(m2), false)
assert(isNothing(m2), true)

const mx = bind([
scope('a', [inRange(5, 15), inc(1)]),
scope('b', [inRange(15, 25), inc(1)]),
scope('c', [inRange(25, 30), inc(1)]),
])

const m3 = mx({ a:10, b:20, c:30 })
assert(m3.value, { a:11, b:21, c:31 })
assert(m3.toBoolean(), true)
assert(isJust(m3), true)
assert(isNothing(m3), false)

const m4 = mx({ a:1, b:20, c:30 })
assert(m4.value, undefined)
assert(m4.toBoolean(), false)
assert(isJust(m4), false)
assert(isNothing(m4), true)

const m5 = mx({ a:10, b:20, c:"lol" })
assert(m5.value, undefined)
assert(m5.toBoolean(), false)
assert(isJust(m5), false)
assert(isNothing(m5), true)

const m6 = mx("lol")
assert(m6.value, undefined)
assert(m6.toBoolean(), false)
assert(isJust(m6), false)
assert(isNothing(m6), true)

const m7 = mx({ a:10, b:20, c:30, d:"lol" })
assert(m7.value, { a:11, b:21, c:31, d:"lol" })
assert(m7.toBoolean(), true)
assert(isJust(m7), true)
assert(isNothing(m7), false)
`

$3

`
$ make # see make help
$ make help # shows all the make commands
$ make build # build stuff puts it in /lib
$ make build-watch # make build but all the time
$ make test # tests the stuff
$ make test-watch # make test but all the time
$ make version # creates a patch tag
$ make version-minor # creates a minor tag
$ make version-major # creates a major tag
$ make publish # publishes the module
``