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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
| package cats | |
| package data | |
| import scala.annotation.tailrec | |
| sealed abstract class Continuation[O, +I] { | |
| def map[I2](fn: I => I2): Continuation[O, I2] = | |
| Continuation.Mapped(this, fn) | |
| def flatMap[I2](fn: I => Continuation[O, I2]): Continuation[O, I2] = |
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
When it comes to encoding data on the pure λ-calculus (without complex extensions such as ADTs), there are 3 widely used approaches.
The Church Encoding, which represents data structures as their folds. Using Caramel’s syntax, the natural number 3 is, for example. represented as:
0 c0 = (f x -> x)
1 c1 = (f x -> (f x))
2 c2 = (f x -> (f (f x)))
This note outlines a principled way to meta-programming in Scala. It tries to combine the best ideas from LMS and Scala macros in a minimalistic design.
LMS: Types matter. Inputs, outputs and transformations should all be statically typed.
Macros: Quotations are ultimately more easy to deal with than implicit-based type-lifting
LMS: Some of the most interesting and powerful applications of meta-programming
Dr. Mark B. Lundeberg, 2018 August 30
bitcoincash:qqy9myvyt7qffgye5a2mn2vn8ry95qm6asy40ptgx2
Since version 2.1, GnuPG is able to use the very same secp256k1 elliptic curve signature algorithm (ECDSA) as used in bitcoin. Quite soon Bitcoin Cash will add a new script opcode OP_CHECKDATASIG that is able to check signatures not just on the containing transaction, but also on arbitrary data. For fun, let's try to intersect the two signature systems and see what can be done!
Listing pods with kubectl get pods, then select a pod name and copy paste it into kubectl logs [pod name]
Dotty contains preliminary support for Scala.js under the flag -scalajs.
Or rather, it contains the infrastructure for preliminary support.
It is far from being actually usable, but this is where you can help!
This small tutorial walks you through a few steps that you can do to further the support of Scala.js in Dotty. Even if you do not typically contribute to a compiler, this can be your chance. It is not very difficult, given that there already exists an extensive test suite, as well as a working implementation for scalac.
The general idea is to run an Emacs server as a daemon which clients can quickly connect to via a bash script. The client executes org-capture and the frame closes upon finalizing or aborting the capture.
The first step is to get an Emacs daemon running as a server with your name of choice. For this example, I’m going to use “capture” as the server name.
| (defvar +org-babel-mode-alist | |
| '((cpp . C) | |
| (C++ . C) | |
| (D . C) | |
| (sh . shell) | |
| (bash . shell) | |
| (matlab . octave) | |
| (amm . ammonite)) | |
| "An alist mapping languages to babel libraries. This is necessary for babel | |
| libraries (ob-*.el) that don't match the name of the language. |