This describes how I setup Atom for an ideal Clojure development workflow. This fixes indentation on newlines, handles parentheses, etc. The keybinding settings for enter (in keymap.cson) are important to get proper newlines with indentation at the right level. There are other helpers in init.coffee and keymap.cson that are useful for cutting, copying, pasting, deleting, and indenting Lisp expressions.
The Atom documentation is excellent. It's highly worth reading the flight manual.
| trait NotSubTypeOf[A, B] // encoding to capture A is not a subtype of B | |
| // Note: We can use infix notation to write `A NotSubTypeOf B` instead of `NotSubTypeOf[A, B]` | |
| // evidence for any two arbitrary types A and B, A is not a subtype of B | |
| implicit def isSub[A, B]: A NotSubTypeOf B = null | |
| // define ambigous implicits to trigger compile error in case A is a subtype of B (or A =:= B) | |
| implicit def iSubAmbig1[A, B >: A]: A NotSubTypeOf B = null | |
| implicit def iSubAmbig2[A, B >: A]: A NotSubTypeOf B = null |
Miles Sabin recently opened a pull request fixing the infamous SI-2712. First off, this is remarkable and, if merged, will make everyone's life enormously easier. This is a bug that a lot of people hit often without even realizing it, and they just assume that either they did something wrong or the compiler is broken in some weird way. It is especially common for users of scalaz or cats.
But that's not what I wanted to write about. What I want to write about is the exact semantics of Miles's fix, because it does impose some very specific assumptions about the way that type constructors work, and understanding those assumptions is the key to getting the most of it his fix.
For starters, here is the sort of thing that SI-2712 affects:
def foo[F[_], A](fa: F[A]): String = fa.toString
Change Apple OS X Dock size from Apple Terminal
defaults write com.apple.dock tilesize -int 32; killall Dock32 is icon size
Copyright © 2016-2018 Fantasyland Institute of Learning. All rights reserved.
A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.
val square : Int => Int = x => x * x
Links on Must watch talks
A Year living Freely - Chris Myers
Programs as Values Pure Composable Database Access in Scala. In general each talk from Rob Norris is very useful for learning.
Tageless Final interpreters are an alternative to the traditional Algebraic Data Type (and generalized ADT) based implementation of the interpreter pattern. This document presents the Tageless Final approach with Scala, and shows how Dotty with it's recently added implicits functions makes the approach even more appealing. All examples are direct translations of their Haskell version presented in the Typed Tagless Final Interpreters: Lecture Notes (section 2).
The interpreter pattern has recently received a lot of attention in the Scala community. A lot of efforts have been invested in trying to address the biggest shortcomings of ADT/GADT based solutions: extensibility. One can first look at cats' Inject typeclass for an implementation of [Data Type à la Carte](http://www.cs.ru.nl/~W.Swierstra/Publications/DataTypesA
