_________ _____ _______________ _____
\_ ___ \\ \\___________ \____ / ____\ ~/.bash/cliref.md
/ \ \/| | | || _/ __ \ __\ copy/paste from whatisdb
\ \___|__ |_|_ || | \ __/|_ | http://pastebin.com/yGmGiDQX
\________ /_____ \_||____|_ /____ /_| [email protected]
20160515 \/ 1527 \/ \/ \/
alias CLIRef.txt='curl -s "http://pastebin.com/raw/yGmGiDQX" | less -i'
| import annotation.unchecked.uncheckedVariance | |
| /** The trait of things that can be compared safely */ | |
| trait Equals[-T] { | |
| /** A witness of Equals' type parameter. Should only used for | |
| * the constraint in EqlDecorator, hence, @uncheckedVariance should not be a problem. | |
| */ | |
| type EqualsDomain = T @uncheckedVariance |
| val n = 9 | |
| val s = Math.sqrt(n).toInt | |
| type Board = IndexedSeq[IndexedSeq[Int]] | |
| def solve(board: Board, cell: Int = 0): Option[Board] = (cell%n, cell/n) match { | |
| case (r, `n`) => Some(board) | |
| case (r, c) if board(r)(c) > 0 => solve(board, cell + 1) | |
| case (r, c) => | |
| def guess(x: Int) = solve(board.updated(r, board(r).updated(c, x)), cell + 1) | |
| val used = board.indices.flatMap(i => Seq(board(r)(i), board(i)(c), board(s*(r/s) + i/s)(s*(c/s) + i%s))) |
There are many tutorials and articles available online which explain functional programming. Examples show small functions, which are composed into others which again get composed. It is hard to imagine how it would all work, then come the analogies and then the math. While the math is necessary to understand it can be difficult to grasp initially. The analogies on the other hand, (at least for me) are not relatable. Some articles assume the reader knows the different terminologies of FP. Over all I felt it is not inviting to learn.
This introduction is for those who have had a tough time understanding those analogies, taken the plunge to functional programming but still have not been able to swim. This is yet another tutorial on functional programming
Functions are first class means they are just like anyone else, or rather they are not special, they behave the same as say primitives or strings or objects.
| /* | |
| * Copyright 2015 Michael Rozumyanskiy | |
| * | |
| * Licensed under the Apache License, Version 2.0 (the "License"); | |
| * you may not use this file except in compliance with the License. | |
| * You may obtain a copy of the License at | |
| * | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * | |
| * Unless required by applicable law or agreed to in writing, software |
These are things that I found annoying writing a complex library in Kotlin. While I am also a Scala developer, these should not necessarily be juxtaposed w/ Scala (even if I reference Scala) as some of my annoyances are with features that Scala doesn't even have. This is also not trying to be opinionated on whether Kotlin is good/bad (for the record, I think it's good). I have numbered them for easy reference. I can give examples for anything I am talking about below upon request. I'm sure there are good reasons for all of them.
| extends CanvasModulate | |
| const NIGHT_COLOR = Color("#091d3a") | |
| const DAY_COLOR = Color("#ffffff") | |
| const EVENING_COLOR = Color("#ff3300") | |
| const TIME_SCALE = 0.1 | |
| var time = 0 |
