Elm version of my F# race paces calculations

race_paces.elm

import Html exposing (text)
import Time exposing (Time)

type UnitType = Metric | Imperial
type Speed = Mph Float | Kph Float
type Pace  = MinPerMile Float | MinPerKm Float
type Distance = Miles Float | Kms Float

speedConversionFactor = 0.621371192

convertMphToKph : Float -> Float
convertMphToKph mph =
  mph / speedConversionFactor
  
convertKphToMph : Float -> Float
convertKphToMph kph =
  kph * speedConversionFactor
  
paceFromSpeed : UnitType -> Speed -> Pace
paceFromSpeed requiredType speed  =
  let 
    asPace spd = 60.0 / spd
  in
    case speed of
      Mph mph ->
        case requiredType of
          Metric -> MinPerKm ( asPace mph |> convertMphToKph )
          Imperial -> MinPerMile ( asPace mph )
      Kph kmh ->
        case requiredType of
          Metric -> MinPerKm ( asPace kmh )
          Imperial -> MinPerMile ( asPace kmh |> convertKphToMph ) 

convertSpeed : UnitType -> Speed -> Speed
convertSpeed requiredType speed  = 
  case speed of
    Mph mph -> 
      case requiredType of
        Metric -> Kph (convertMphToKph mph) 
        Imperial -> speed
    Kph kph ->
      case requiredType of
        Metric -> speed
        Imperial -> Mph (convertKphToMph kph)

calcSpeedFromTimeAndDistance : Time -> Distance -> UnitType -> Speed
calcSpeedFromTimeAndDistance time distance requiredType =
  let 
    speed dist = dist / (time |> Time.inHours)
  in 
    case distance of
      Miles miles -> Mph (speed miles) |> convertSpeed requiredType
      Kms kms -> Kph (speed kms) |> convertSpeed requiredType

calcPaceFromTimeAndDistance : Time -> Distance -> UnitType -> Pace
calcPaceFromTimeAndDistance time distance requiredType =
  calcSpeedFromTimeAndDistance time distance requiredType |> paceFromSpeed requiredType

main =
  let 
    requiredTimeMins = 1 * Time.minute
    distance = Kms 0.4
    speedCalc = calcPaceFromTimeAndDistance requiredTimeMins distance
    test = Mph (12) |> convertSpeed Metric
  in
    text (toString (speedCalc Metric))
    -- text ( toString test )