Blog: Mr. Mathiesen

F# - FSharp is surprisingly expressive

March 06, 2014.

Code Snippet:

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open System

type System.Int32 with
  member x.Months = DateTime.Today.AddMonths(x) - DateTime.Today
  member x.Years = DateTime.Today.AddYears(x) - DateTime.Today

type System.Double with
  member x.Days = DateTime.Today.AddDays(x) - DateTime.Today

type System.TimeSpan with
  member x.Ago = DateTime.Now.Add(-x)
  member x.FromNow = DateTime.Now.Add(x)
  member x.FromToday = DateTime.Today.Add(x)

let foo = DateTime.Now - 20 .Years - 0.5 .Days
let bar = 50 .Years.Ago

Code output:

type Int32 with
  member Months : System.TimeSpan
type Int32 with
  member Years : System.TimeSpan
type Double with
  member Days : System.TimeSpan
type TimeSpan with
  member Ago : System.DateTime
type TimeSpan with
  member FromNow : System.DateTime
type TimeSpan with
  member FromToday : System.DateTime
> val foo : System.DateTime = 03/06/1994 10:26:59
> val bar : System.DateTime = 03/05/1964 22:28:15

References: