Successive fold functions

fold by applying a list of function to a list of arg, last one behaving as usual

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let sa = [ 1 .. 10 ]

let rec fold f s xs = 
   match xs with 
   | [] -> s
   | x::xs  ->  fold  f (f s x) xs
fold (+) 0 sa

let rec foldps f s xs k = 
   match xs with 
   | [] -> k s 
   | x::xs  -> foldps f s xs (fun s  -> f x s k)  

let pluscps = (fun x s cont -> cont(s + x))
foldps pluscps 0 sa id

let rec foldpsn fs s xs k = 
   match xs with 
   | [] -> k s 
   | x::xs  -> match fs with
               | f::[] -> foldps  f  s xs (fun s  -> f x s k)
               | f::fs -> foldpsn fs s xs (fun s  -> f x s k)
               | _     -> failwith "not good"


let printcps = (fun x s cont -> printfn "%A" x;cont(s))
foldpsn [printcps;pluscps] 0 sa id

val sa : int list

Full name: Script.sa

val fold : f:('a -> 'b -> 'a) -> s:'a -> xs:'b list -> 'a

Full name: Script.fold

val f : ('a -> 'b -> 'a)

val s : 'a

val xs : 'b list

val x : 'b

val foldps : f:('a -> 'b -> ('b -> 'c) -> 'c) -> s:'b -> xs:'a list -> k:('b -> 'c) -> 'c

Full name: Script.foldps

val f : ('a -> 'b -> ('b -> 'c) -> 'c)

val s : 'b

val xs : 'a list

val k : ('b -> 'c)

val x : 'a

val pluscps : x:int -> s:int -> cont:(int -> 'a) -> 'a

Full name: Script.pluscps

val x : int

val s : int

val cont : (int -> 'a)

val id : x:'T -> 'T

Full name: Microsoft.FSharp.Core.Operators.id

val foldpsn : fs:('a -> 'b -> ('b -> 'c) -> 'c) list -> s:'b -> xs:'a list -> k:('b -> 'c) -> 'c

Full name: Script.foldpsn

val fs : ('a -> 'b -> ('b -> 'c) -> 'c) list

val failwith : message:string -> 'T

Full name: Microsoft.FSharp.Core.Operators.failwith

val printcps : x:'a -> s:'b -> cont:('b -> 'c) -> 'c

Full name: Script.printcps

val cont : ('b -> 'c)

val printfn : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printfn

Raw view Test code New version

More information

Link:	http://fssnip.net/e2
Posted:	12 years ago
Author:	nicolas2
Tags:	fold , cps