module SentenceParser

open Parser

let period = (pchar '.') <!> "period"
let word = pfun (pmany1 pletter) (fun cs -> stringify cs) <!> "word"
let upperword = pseq pupper (pmany0 pletter) (fun (x,xs) -> stringify (x::xs)) <!> "upperword"
let words0 = pmany0 (pright pws1 word) <!> "words0"
let prefix = pseq upperword words0 (fun (w,ws) -> w::ws) <!> "sprefix"
let sentence = pleft prefix period <!> "sentence"
let grammar = pleft sentence peof <!> "grammar"

let parse input : string list option =
    match grammar (prepare input) with
    | Success(ws,_) -> Some ws
    | Failure -> None