This guide assumes you're working on a Unix-like environment. I'm using Linux Mint (Ubuntu). It should work on Macs, and might on Windows.
These are the four steps you can use as a checklist, see the headings below for the details on each step.
~/.authinfo.gpg
Kinesis Freestyle (Terrible key switches. Mushy and un-lovable)
Kinesis Freestyle Edge (Traditional layout with too many keys, mech switches, proably too big to be tented easily/properly)
Matias Ergo Pro (Looks pretty great. Have not tried.)
ErgoDox Kit (Currently, my everyday keyboard. Can buy pre-assembled on eBay.)
ErgoDox EZ (Prolly the best option for most people.)
| {-# LANGUAGE RankNTypes #-} | |
| import Prelude hiding (Maybe, Just, Nothing, maybe) | |
| data Maybe a = Maybe {maybe :: forall r . r -> (a -> r) -> r} | |
| nothing = Maybe (\nothing' just' -> nothing') | |
| just x = Maybe (\nothing' just' -> just' x) | |
| instance (Show a) => (Show (Maybe a)) where |
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
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
| // Basic setup | |
| interface Exp | |
| data class Lit(val x: Int): Exp | |
| data class Add(val x: Exp, val y: Exp): Exp | |
| interface IntAlg<A> | |
| { | |
| fun lit(x: Int): A | |
| fun add(x: A, y: A): A |
Delimited continuations manipulate the control flow of programs. Similar to control structures like conditionals or loops they allow to deviate from a sequential flow of control.
We use exception handling as another example for control flow manipulation and later show how to implement it using delimited continuations. Finally, we show that nondeterminism can also be expressed using delimited continuations.