SteveGilham

let state = ref 0;;

SteveGilham

(!): ‘a ref -> ‘a

!state;;

SteveGilham

(:=) : ‘a ref -> ‘a -> unit

state := 1;;

SteveGilham

type 'a Ref = { mutable value : 'a }
let (!) (r : 'a Ref) = r.value
let (:=) (r : 'a Ref) (v:'a) = r.value <- v;;

SteveGilham

let gen f =
  let i = ref 0
  fun () -> (i := !i + 1; f !i);;

SteveGilham

let sq x = x*x;;
let g = gen sq;;

SteveGilham

let hd (x::xs) = x;;
let tl (x::xs) = xs;;

SteveGilham

let stream init =
  let state = ref init
  let put x = (state := (!state)@[x])
  let get () = let r = hd !state
               state := tl !state
               r
  let isEmpty () = !state = []
  (put, get, isEmpty);;

SteveGilham

let spawn f = (new Thread(new ThreadStart(f))).Start();;

SteveGilham

let getLock () = new ReaderWriterLock();;
let acquireWrite (lock:ReaderWriterLock) = lock.AcquireWriterLock(-1);;
let releaseWrite (lock:ReaderWriterLock) = lock.ReleaseWriterLock();;
let acquireRead (lock:ReaderWriterLock) = lock.AcquireReaderLock(-1);;
let releaseRead (lock:ReaderWriterLock) = lock.ReleaseReaderLock();;
let upgrade (lock:ReaderWriterLock) = lock.UpgradeToWriterLock(-1);;
let downgrade (lock:ReaderWriterLock) cookie = lock.DowngradeFromWriterLock(cookie);;