CarstenKoenig

// translated from http://www.haskellforall.com/2012/06/you-could-have-invented-free-monads.html

// we need our functor that will define the DSL more or less
type Command<'next> =
    | Output of string * 'next
    | Bell of 'next
    | Done

// we need the fmap for the functor
let fmap f = function

CarstenKoenig

// Projektion

type Key = int

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

CarstenKoenig

type Movement =
    | Left of int
    | Right of int

type MovementState<'a> = Movement list -> Movement list * 'a

type MovementBuilder () =
    member x.Zero () : MovementState<unit> = fun st -> (st, ())
    member __.Return x : MovementState<'a> = fun st -> (st, x)
    member __.Bind(m: MovementState<'a>, f) = 

CarstenKoenig

// Algorithmus
// (DE) http://ccd-school.de/coding-dojo/function-katas/russische-bauernmultiplikation/
// (EN) https://en.wikipedia.org/wiki/Ancient_Egyptian_multiplication

let rec mul a b =
    match a with
        | 1                -> b
        | a when a <= 0    -> 0
        | a when x % 2 = 0 -> mul (a/2) (b*2)
        | a                -> mul (a/2) (b*2) + b

CarstenKoenig

{----------------------------------------------------------------------
- CCD Function Kata
- Russische Bauernmultiplikation
-
- siehe: http://ccd-school.de/coding-dojo/function-katas/russische-bauernmultiplikation/
-
- 
- Erklärung:
- ---------
- wie das funktioniert versteht am am einfachsten, wenn man sich die linke

CarstenKoenig

(***********************************************************************
* CCD Function Kata
* Russische Bauernmultiplikation
*
* siehe: http://ccd-school.de/coding-dojo/function-katas/russische-bauernmultiplikation/
*
* 
* Erklärung:
* ---------
* wie das funktioniert versteht am am einfachsten, wenn man sich die linke

CarstenKoenig

(*****************************************************************************************
* Task:
* =====
*
* There is a string which may contain asterisks. Each asterisk must be replaced by
* a 0 or 1 and then all possible output combinations must be printed out.
* 
* For example the strings
*
* a*b must produce two outputs a0b and a1b

CarstenKoenig

module EightQ where

import Control.Monad (foldM)

type Queen = (Int,Int)

{-----------------------------------------------------------------------
Questions:
- would you consider `queens` readable?
- what about understanding?

CarstenKoenig

module Matrizen

import Data.Vect

Matrix : (Nat, Nat) -> Type -> Type
Matrix (n,m) a = Vect n (Vect m a)


scalProd : Num a => Vect n a -> Vect n a -> a
scalProd xs ys = sum $ zipWith (*) xs ys

CarstenKoenig

module List =

    type Item = { value : int; next : List }
    and  List = Item option ref

    let empty : List = ref None
    let singleton x = { value = x; next = ref None }

    let rec append x l =
        let item = singleton x