Elm Insights: Article on Pipelining

elm_insights_farewell_backticks_hello_pipeline.elm

{-

  To run in elmO (elm Online Editor): copy n paste into http://elm-lang.org/try
  
  New andThen Pipeline Pattern, replaces `andThen` infix operation
      introduced in v0.18 to  
                     Result.andThen
                     Maybe.andThen
                     Json.Decode.andThen
                     Task.andThen

--}

import Html exposing (text, div, li, a)
import Html.Attributes as Attributes exposing (style, href)

--Last callback in andThen Pipeline
isFloatBetweenZeroAnd100: Float -> Result String Float 
isFloatBetweenZeroAnd100 num =
    if num >= 0.0 && num <= 100.0 then
      Ok (num * 10) 
     else 
      Err "Not a number between 0.0 and 100.0"


--andThen Pipeline Pattern
changeIntStringToFloatnRaiseItBy10: String -> Result String Float
changeIntStringToFloatnRaiseItBy10   str = 
               (String.toInt str)
                                |>Result.andThen (\x -> String.toFloat( toString x)) -- inline anonymous callback
                                |>Result.andThen (isFloatBetweenZeroAnd100 )

main =
 div[
          Attributes.style[
                              ("padding", "30px")
                             ,("color", "red")
          ]
     ] [  text <| toString <| changeIntStringToFloatnRaiseItBy10 "24" 
          ,li[style[ ("padding-top", "50px")
                            ,("color", "skyblue")
                    ] ]
           [   
                a [  
                     href "https://medium.com/@kkruups/elm-insights-c067c66161bb#.2dnoytme1" 
                    ,style[ ("padding-top", "50px")
                            ,("color", "dodgerblue")
                            ,("font-style", "italic")
                    ] 
                ][ 
                     text "elm Insights: Farewell Backticks, Hello Pipeline" 
           ]
         ]
     ]