elm-package.json

{
    "version": "0.0.0",
    "summary": "Markdown Preview",
    "description": "A quick markdown previewer in Elm.",
    "license": "BSD3",
    "source-directories": [
        "."
    ],
    "exposed-modules": [],
    "dependencies": {
        "elm-lang/core": "1.0.0 <= v < 2.0.0",
        "evancz/elm-html": "1.0.0 <= v < 2.0.0"
    },
    "repository": "https://gist.github.com/capicue/9565df3f0850a24a6ad3"
}

Markdown.elm

import Html (..)
import Html.Attributes (..)
import Html.Events (..)
import Signal ((<~), Signal)
import Signal
import Markdown


-- MODEL --

type alias Model = String

emptyModel : Model
emptyModel = ""


-- UPDATE --

type Action
  = NoOp
  | UpdateField String

update : Action -> Model -> Model
update action model =
  case action of
    NoOp -> model
    UpdateField str -> str


-- VIEW--

view : Model -> Html
view model =
  div
    []
    [ textarea
        [ placeholder "Type Markdown Here"
        , value model
        , autofocus True
        , cols 80
        , rows 20
        , on "input" targetValue (Signal.send updates << UpdateField)
        ]
        [],
      p [] [ Markdown.toHtml model ]
    ]


-- INPUTS --

main : Signal Html
main = view <~ model

model : Signal Model
model = Signal.foldp update emptyModel (Signal.subscribe updates)

updates : Signal.Channel Action
updates = Signal.channel NoOp