make the dates prettier

(wrote this module in the last few hours, only adding it now.)

elm/PrettyDate.elm

module PrettyDate (prettyDate) where
import Date
import Date (Date)
prettyDate : Date -> Date -> String
prettyDate reference date =
    let referenceSeconds = Date.toTime reference
        dateSeconds = Date.toTime date
        diffSeconds = referenceSeconds - dateSeconds
    in format diffSeconds
format : Float -> String
format diff =
    let minute = 60 * 1000
        hour = 60 * minute
        day = 24 * hour
        week = 7 * day
        month = 31 * day
        year = 365 * day
        roundToString = toString << ceiling
    in if | diff < minute -> "moments ago"
          | diff < hour   -> roundToString (diff / minute) ++ " minutes ago"
          | diff < day    -> roundToString (diff / hour)   ++ " hours ago"
          | diff < week   -> roundToString (diff / day)    ++ " days ago"
          | diff < month  -> roundToString (diff / week)   ++ " weeks ago"
          | diff < year   -> roundToString (diff / month)  ++ " months ago"
          | otherwise     -> roundToString (diff / year)   ++ " years ago"

elm/Stream.elm

import Html.Attributes as Attr
import List
import String
import PrettyDate (prettyDate)
type alias Post = { title:String, content:String, created:Date }
referenceDate = date "2015-03-01T14:09"
viewDate : Date -> Html
viewDate d = let isoDate = formatDate "%Y-%m-%dT%H:%M:%SZ" d
             in time [Attr.title isoDate, Attr.datetime isoDate] [(text isoDate)]
viewDate d = let dateString = prettyDate referenceDate d
                 isoDate = formatDate "%Y-%m-%dT%H:%M:%SZ" d
             in time [Attr.title isoDate, Attr.datetime isoDate] [(text dateString)]
viewPost : Post -> Html
viewPost post = div [] [