KatsApril.fsx

open System

type Result =
  | IsPanagram
  | NotPanagram

let (|RightSize|) (s:string) = s.Length > 1 && s.Length < 1000 


let isPanagram (s: string) =
  let checkActual aceptedChar (s:string) =
    let phraseSet = s.ToLower().Replace(" ", String.Empty) |> Set.ofSeq
    let acceptedSet = Set.ofSeq aceptedChar    
    if phraseSet.IsSupersetOf acceptedSet then IsPanagram
    else NotPanagram

  match s with
  | RightSize true -> checkActual (seq ['a'..'z']) s |> Some
  | _ -> None


let pan = "The quick brown fox jumps over the lazy dog"
let pan2 = "The quick brown fox jumps over the lazy dog."
let s = @"We promptly judged antique ivory buckles for the next pri "

isPanagram pan
isPanagram "ee" 
isPanagram s
isPanagram pan2
isPanagram ""