continuable fp
Continuable operators, but with the arguments flipped so they compose better, and also they curry automatically. So this is operator(function, data).
This is a fun way to play with IO and functional patterns.
install
npm i -S continuable-fp
example
var compose = require('compose-function')
var c = require('./')
var excitedly = compose(
// remove a level of nesting
c.join,
c.map(function (data) {
// return a nested continuable
// here you can make a call to a new continuable (`someIO` below),
// using the data inside this continuable
return c.either(
// call this if `someIO` returns an error
function onErr (err) {
return c.of('booo')
},
function (val) {
return c.of(val)
},
someIO(data + ' wooo')
)
}),
c.map(function (data) {
return data + '!!!'
})
)
excitedly(someIO('this is a value'))(function (err, val) {
console.log(err, val)
// null 'this is a value!!! wooo'
})
function someIO (data, cb) {
if (!cb) return function (_cb) {
return someIO(data, _cb)
}
process.nextTick(function () {
cb(null, data)
})
}
function ioError (data, cb) {
if (!cb) return function (_cb) {
return ioError(data, _cb)
}
process.nextTick(function () {
cb(new Error('rarrr'))
})
}example of errors
var c = require('./')
var myFn = c.either(
function onErr (err) {
return c.of(err + ' baaaa')
},
function onData (data) {
return c.of('ok')
}
)
myFn(someIO('woooo'))(function (err, done) {
console.log('it worked...', err, done)
// it worked... null ok
})
myFn(ioError('booo'))(function (err, ok) {
console.log('err result...', err, ok)
// err result... null Error: booo baaaa
})
function someIO (data, cb) {
if (!cb) return function (_cb) {
return someIO(data, _cb)
}
process.nextTick(function () {
cb(null, data)
})
}
function ioError (data, cb) {
if (!cb) return function (_cb) {
return ioError(data, _cb)
}
process.nextTick(function () {
cb(new Error('' + data))
})
}$ node err-example.js
it worked... null ok
err result... null Error: booo baaaa
typescript
You can use typescript too
$ npx tsc ts-example.ts
ts-example.ts:7:9 - error TS2339: Property 'thisdoesnotexist' does not exist on type 'string'.
7 val.thisdoesnotexist()
~~~~~~~~~~~~~~~~
import c = require('continuable-fp')
var test: c.Continuable<string> = c.of('hello')
c.of('hello')(function (err, val) {
val.thisdoesnotexist()
// Property 'thisdoesnotexist' does not exist on type 'string'
})operators
join
Take a nested continuable and return the inner one
map
Map a value through a predicate function
either
Return the left function if there is an error, right function if there's no error.
either (left, right, continuable)of
Take a value, and create a continuable of it
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