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module Make (M : Intf.Core) = struct
type 'a cont = { cont : 'b. ('a M.t -> 'b M.t) -> 'b M.t } [@@unboxed]
type 'a m = 'a M.t
type 'a t = handler:handler -> 'a cont
and handler = { handler : 'a. 'a payload -> 'a cont } [@@unboxed]
and 'a payload = Dist of 'a Dist.t m | Score of 'a m * Log_space.t m
type 'a res = handler:handler -> 'a M.res
let return x : 'a t = fun ~handler:_ -> { cont = (fun k -> k (M.return x)) }
let if_ cond body ~handler =
{ cont =
(fun k ->
(cond ~handler).cont @@ fun cond ->
M.if_ cond (fun c -> (body c ~handler).cont k))
}
let map (type a b) (m : a t) (f : a -> b) : b t =
fun ~handler ->
{ cont = (fun k -> (m ~handler).cont @@ fun m -> k (M.map m f)) }
let map2 (type a b c) (m : a t) (m' : b t) (f : a -> b -> c) : c t =
fun ~handler ->
{ cont =
(fun k ->
(m ~handler).cont @@ fun m ->
(m' ~handler).cont @@ fun m' -> k @@ M.map2 m m' f)
}
let map_array (type a b) (m : a t array) (f : a array -> b) : b t =
fun ~handler ->
{ cont =
(fun k ->
Array.fold_left
(fun k m acc -> (m ~handler).cont @@ fun m -> k (m :: acc))
(fun l -> k @@ M.map_array (Array.of_list (List.rev l)) f)
m
[])
}
let bind (m : 'a t) (f : 'a -> 'b t) : 'b t =
fun ~handler ->
{ cont =
(fun k ->
(m ~handler).cont @@ fun m ->
M.bind m @@ fun m -> (f m ~handler).cont k)
}
let log_score : Log_space.t -> unit t =
fun s ~handler ->
{ cont =
(fun k -> (handler.handler (Score (M.return (), M.return s))).cont k)
}
let score s = log_score (Log_space.of_float s)
let map_log_score : type a. a t -> (a -> Log_space.t) -> a t =
fun m f ~handler ->
{ cont =
(fun k ->
(m ~handler).cont @@ fun m ->
let s = M.map m f in
(handler.handler (Score (m, s))).cont k)
}
let map_score m f = map_log_score m (fun x -> Log_space.of_float (f x))
let samplei (d : 'a Dist.t t) ~handler =
{ cont =
(fun k ->
(d ~handler).cont @@ fun d -> (handler.handler (Dist d)).cont k)
}
let sample (d : 'a Dist.t) ~handler =
{ cont = (fun k -> (handler.handler (Dist (M.return d))).cont k) }
let run (m : 'a t) : 'a res =
fun ~handler -> M.run @@ (m ~handler).cont Fun.id
module Infix = struct
let ( let* ) = bind
let ( let+ ) = map
let ( and+ ) m m' = map2 m m' (fun x y -> (x, y))
let ( >|= ) = map
let ( >>= ) = bind
let ( >>=$ ) = score
let return = return
end
end
[@@inline]