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fiddle.fsx
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fiddle.fsx
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type Vide<'v,'s,'c> = Vide of ('s option -> 'c -> 'v * 's)
type VideBuilder() =
member inline _.Bind
(
Vide m: Vide<'v1,'s1,'c>,
f: 'v1 -> Vide<'v2,'s2,'c>
)
=
Vide <| fun s c ->
let ms,fs =
match s with
| None -> None,None
| Some (ms,fs) -> Some ms, Some fs
let mv,ms = m ms c
let (Vide v) = f mv
let vres,fs = v fs c
vres, (ms,fs)
member inline _.Return(x) =
Vide <| fun s c -> x,None
let vide = VideBuilder()
let toStateMachine ctx (Vide vide: Vide<'v,'s,'c>) =
let mutable state = None
fun () ->
let value,newState = vide state ctx
state <- Some newState
value
// -----
let inline counter inclStart inc =
Vide <| fun s c ->
let s = s |> Option.defaultValue inclStart
s, s + inc
// -----
let eval =
toStateMachine None <| vide {
let! c1 = counter 0 1
let! c2 = counter 100 10
return c1 + c2
}
// -----
eval()