dot.elm

import Graphics.Element exposing (..)
import Graphics.Input.Field as Field
import List
import String

{-- http://www.reddit.com/r/dailyprogrammer/comments/2qxrtk/20141231_challenge_195_intermediate_math_dice/cnawmtn --}

{-- 

based on https://hackage.haskell.org/package/split-0.1.1/docs/Data-List-Split.html

add to https://github.com/circuithub/elm-list-extra/blob/2.3.1/src/List/Extra.elm

module List.Extra 
    ( groupInto
    , collect
    ) where
--}

{-| 
@docs groupInto
-}

{-| splitEvery n splits a list into length-n pieces. The last piece will be shorter if n does not evenly divide the length of the list. 
-}

splitEvery : Int -> List a -> List (List a)
splitEvery n l =
    let 
        loop : Int -> List a -> List (List a) -> List (List a)
        loop n rem acc =
            case rem of 
                []  -> acc |> List.reverse
                _   -> loop n (List.drop n rem) ((List.take n rem)::acc)
    in
        loop n l []

{-| collect iterates over each element of the list, applies the given function. Concatenates all the results and returns the combined list.
-}
collect : (a -> List a') -> List a -> List a'
collect f l = List.map (\x -> f x) l |> List.concat


iteri : (int -> a) -> List a -> List -> ()
iteri = ()

mapi : (int -> a -> a') -> List a -> List a'
mapi f l = zip [0..(List.length l) |> List.map (\(i,x) -> f i x)

{-- http://stackoverflow.com/questions/1526046/f-permutations --}
splitList : List a -> List (List a)
splitList l = case l of
    [x]  -> [x, []]
    x::xs -> (x,xs)::(List.map (\(y, l) -> y,(x::l))) (splitList xs)

permutations : List a -> List (List a)
permutations l = case l of
    []    -> [[]]
    x::xs -> splitList l
             |> collect (\(x, xs) -> permutations xs |> List.map (\l -> x::l))

content : Signal.Mailbox Field.Content
content = 
    Signal.mailbox Field.noContent
 
main : Signal Element
main =
    Signal.map scene content.signal

scene : Field.Content -> Element
scene fieldContent = 
    flow down
    [ Field.field Field.defaultStyle (Signal.message content.address) "List of stuff?" fieldContent
    , show (String.split " " fieldContent.string |> List.filter (\x -> (String.length x) > 0) |> splitEvery 3)
    ]