CarstenKoenig

type Probability = double
type Distribution<'a> = ('a * Probability) list
type Event<'a> = 'a -> bool

let printDistribution (v : Distribution<'a>) =
    let negate x = -x
    v |> List.sortBy (snd >> negate) |> List.iter (fun (a,p) -> printfn "%A: %.2f%%" a (p * 100.0))

let sure (a : 'a) : Distribution<'a> =
    [a, 1.0]

CarstenKoenig

type List<'i,'r> = Nil | Cons of 'i*'r

type FixList<'i> = FixList of List<'i,FixList<'i>>

let rec fmap (f : 'a -> 'b) (l : List<'i,'a>) : List<'i,'b> =
    match l with
    | Nil            -> Nil
    | Cons (x, tail) -> Cons (x, f tail)

// you can express hylo directly without using ana and cata (by either following the

CarstenKoenig

module SimpleDep

basic : (b : Bool) -> if b then String else Int
basic True = "it's true"
basic False = 0

-------------

data WhatIsIt = AString | AInt

CarstenKoenig

{-# LANGUAGE GADTs #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE KindSignatures #-}

module DepFun where

data Nat = NatZ | NatS Nat

type family Codom (n :: Nat) where

CarstenKoenig

// Projektion

type Key = int

type Projection<'ev,'st,'res> =
    {
        init : Key -> 'st
        fold : 'st -> 'ev -> 'st
        final : 'st -> 'res
    }

CarstenKoenig

{-# LANGUAGE PartialTypeSignatures #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GADTs #-}


module FinVec where

-- simple representation of naturals
-- DataKinds lifts this to the type-level

CarstenKoenig

{-# LANGUAGE InstanceSigs #-}
module ReaderM where

import Control.Monad.Reader
import Control.Monad.State.Strict
import Data.Functor.Identity

data Config = Config { nr :: Int }

main :: IO ()

CarstenKoenig

#!/usr/bin/env stack
-- stack --resolver lts-9.5 script --package scotty

{-# LANGUAGE OverloadedStrings #-}

import Web.Scotty

import Data.Monoid (mconcat)

main = scotty 3000 $ do

CarstenKoenig

module Main where

import Control.Concurrent (threadDelay, MVar, newEmptyMVar, putMVar, tryTakeMVar)

import Data.Maybe (isJust)

import System.IO (hSetBuffering, BufferMode(NoBuffering), stdout)
import System.Posix.Signals (installHandler, Handler(Catch), sigINT, sigTERM)

CarstenKoenig

1. Getting Stack on Ubuntu

I would actually use the installer script:

sudo curl -sSL https://get.haskellstack.org/ | sh

but an older version is on official sources as well (better to the upgrade after)

sudo apt install haskell-stack
stack upgrade