bkyrlach

sealed trait Thing[+A]

object Thing {
  case class SomeThing[A](value: A, next: Thing[A]) extends Thing[A]
  case object NotAThing extends Thing[Nothing]
}

bkyrlach

Require Import String.

Inductive ty : Type :=
  | TInt : ty
  | TString : ty.

Inductive Value : Type :=
  | VInt : nat -> Value
  | VString : string -> Value.

bkyrlach

module Traverse where

import Prelude hiding (Monad, Functor, Either, Left, Right, map, traverse, pure)

-- So, you probably already have a natural intuition for
-- the fact that types are similar to the idea of sets
-- from mathematics.

-- So, lets imagine all of the sets (types) we can describe
-- in Haskell. We understand how to work with the inhabitants

bkyrlach

module Combining where

import Prelude hiding (Semigroup)
import Data.List as List

-- We know that lots of things can be combined together.

combineLists :: [a] -> [a] -> [a]
combineLists [] [] = []
combineLists [] ys = ys

bkyrlach

module Pangram where

import Data.Set (Set)
import Data.Set as Set

import Data.Char (toLower, isLetter)

import Data.List as List

isPangram :: [Char] -> Bool

bkyrlach

{-# LANGUAGE GeneralizedNewtypeDeriving #-}

module Age where

main :: IO ()
main = do
    print "Hello, world."
    print $ show $ ageOn Mecury (earthYearInSeconds * 38)

data Planet =

bkyrlach

sealed trait AST

case class Query(selectClause: List[ColumnExp], ...) extends AST

sealed trait Exp extends AST

sealed trait QIdent extends Exp
case class QIdentBase(name: String) extends QIdent
case class QIdentDot(qualifier: QIdent, name: QIdentBase) extends QIdent

bkyrlach

sealed trait DaxcoError
case object NotFound extends DaxcoError
case object NoClasses extends DaxcoError
case object ClassFull extends DaxcoError

def someApiCall(someInput: ???): IO[Either[DaxcoError,???]] = ...

bkyrlach

import java.util.concurrent.Executors

import cats.effect._
import cats.implicits._
import org.http4s.{HttpApp, HttpRoutes}
import org.http4s.syntax._
import org.http4s.dsl.io._
import org.http4s.implicits._
import org.http4s.server.Router
import org.http4s.server.blaze._

bkyrlach

package com.kyrlach.coinflip;

import java.util.Random;
import java.util.Scanner;

public class Program {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        Random r = new Random();
        System.out.println("Hello.");