fsharp-transducer

transducer implementation for F#

Introduction

• This is a F# implementation of Clojure's transducer lib
• Clojure's transducer: https://clojure.org/reference/transducers

Usage

open fsharp_transducer.Folds

let strTransducer (prefix: string) (xf: Reducer<string, string list>) (data: TransducerArgs<'a, string list>) =
	match data with
	| Init  -> Reduced []
	| Complete acc -> Reduced acc
	| Step(item, acc) -> 
		let itemStr = item.ToString()
		xf (Step(prefix + ":" + itemStr, acc))

let conj b a = [a] @ b
let isOdd v = (v % 2) <> 0
let list1 = [1; 2; 3; 4; 5]
let a = transduce (strTransducer "hi") conj [] list1 // ["hi:5"; "hi:4"; "hi:3"; "hi:2"; "hi:1"]
let mystrTrans1 = strTransducer "hi1"
let mystrTrans2 = strTransducer "hi2"
let b = transduce (comp mystrTrans1 mystrTrans2) conj [] list1 // ["hi2:hi1:5"; "hi2:hi1:4"; "hi2:hi1:3"; "hi2:hi1:2"; "hi2:hi1:1"]
let c = sequence (strTransducer "hi") list1 // sequence returns a cached lazy seq, c=cached-seq("hi:1", "hi:2", "hi:3", "hi:4", "hi:5")
Seq.iteri (fun index item ->
    printfn "c[%d]=%A" index item
) c
Seq.iteri (fun index item ->
    printfn "c[%d]=%A" index item
) c
let c2 = eduction (strTransducer "hi") list1 // eduction returns a lazy seq, c2=seq("hi:1", "hi:2", "hi:3", "hi:4", "hi:5")
Seq.iteri (fun index item ->
    printfn "c2[%d]=%A" index item
) c2
Seq.iteri (fun index item ->
    printfn "c2[%d]=%A" index item
) c2
let d = into ["hello"] (strTransducer "hi") list1 // ["hello"; "hi:1"; "hi:2"; "hi:3"; "hi:4"; "hi:5"]
let e = into [0] (filter isOdd) list1 // [0; 1; 3; 5]
let f = into ["map-demo"] (comp mystrTrans1 (map (fun x->"map-"+x))) list1 // ["map-demo"; "map-hi1:1"; "map-hi1:2"; "map-hi1:3"; "map-hi1:4"; "map-hi1:5"]
let take3 = into [] (take 3) list1 // [1; 2; 3]
let skip2 = into [] (skip 2) list1 // [3; 4; 5]
let partitionByOdd = transduce (partition isOdd) (fun pr item->pr) ([], []) list1 // ([1; 3; 5], [2; 4])
let distinctValues = into [] distinct [1; 2; 3; 2; 1] // [1; 2; 3]