Dennis Vennink dennisvennink

Getting set up with Cayley and Postgres (April 2018)

Initialize the database

$ createdb testdb
$ wget https://github.com/cayleygraph/cayley/releases/download/v0.7.2/cayley_0.7.2_darwin_amd64.tar.gz
$ tar zxvf cayley_0.7.2_darwin_amd64.tar.gz
$ cat >cayley.cfg.json
{
  "store": {

Rust/Haskell: Higher-Kinded Types (HKT)

A higher kinded type is a concept that reifies a type constructor as an actual type.

A type constructor can be thought of in these analogies:

like a function in the type universe
as a type with a "hole" in it

	// This example shows how higher-kinded types can be emulated in Swift today.
	// It acheives correct typing at the cost of some boilerplate, manual lifting and an existential representation.
	// The technique below was directly inspired by the paper Lightweight Higher-Kinded Polymorphism
	// by Jeremy Yallop and Leo White found at http://ocamllabs.io/higher/lightweight-higher-kinded-polymorphism.pdf

	/// `ConstructorTag` represents a type constructor.
	/// `Argument` represents an argument to the type constructor.
	struct Apply<ConstructorTag, Argument> {
	/// An existential containing a value of `Constructor<Argument>`
	/// Where `Constructor` is the type constructor represented by `ConstructorTag`

	import Foundation

	extension UnicodeScalar : ForwardIndexType {
	public func successor() -> UnicodeScalar {
	return UnicodeScalar(value + 1)
	}
	}

	var operatorHeads: [UnicodeScalar] = Array("=-+!*%<>&\|^~?".unicodeScalars)
	operatorHeads += Array("\u{00A1}" ... "\u{00A7}")