Created
May 21, 2015 20:02
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| var fs = require('fs') | |
| var Either = require('fantasy-eithers') | |
| var Option = require('fantasy-options') | |
| var Promise = require('fantasy-promises') | |
| var EitherT = Either.EitherT | |
| var OptionT = Option.OptionT | |
| var EitherPromise = EitherT(Promise) | |
| var OptionEitherPromise = OptionT(EitherT(Promise)) | |
| var identity = function (x) { return x } | |
| var read = function (filename) { | |
| return new Promise(function (resolve) { | |
| fs.readFile(filename, function (err, data) { | |
| //return resolve(err ? Either.Left(err) : Either.Right(Option.Some(data.toString()))) | |
| return resolve(err ? Either.Left(err) : Either.Right(filename === 'tst.js' ? Option.None : Option.Some(data.toString()))) | |
| }) | |
| }) | |
| } | |
| var take100 = function (data) { | |
| return data.slice(0,100) | |
| } | |
| var lifted_read = function (filename) { | |
| return OptionEitherPromise(EitherPromise(read(filename))) | |
| } | |
| var on_error = function (err) { | |
| console.log('Can\'t we just not have errors?') | |
| console.error(err) | |
| } | |
| var on_success = function (data) { | |
| console.log(data) | |
| } | |
| lifted_read('tst.js') | |
| .map(take100) | |
| .orElse(lifted_read('tst2.js')) | |
| .getOrElse('no diggity') | |
| .fold(on_error, on_success) | |
| .fork(identity) |
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