string calculator

gistfile1.fs

let lToS (l:char list) = System.String.Concat(Array.ofList(l))

let sumString = 
	let parse (l:string) =
		let guessDelimeter (l:string) = 
			match Seq.toList l with
				| '/'::'/'::c::'\n'::_ -> c
				| _ -> Seq.find (fun i -> i = ',' || i = '\n') l
		let valuePart = (fun (s:string) ->
			match Seq.toList s with
				| '/'::'/'::c::'\n'::r -> r
				| v -> v) >> lToS
		Array.map int ((valuePart l).Split(guessDelimeter l))
	
	(parse >> Array.fold (fun acc i -> acc + i ) 0)

sumString "3,9,11" |> printfn "%d"
sumString "3\n9\n11" |> printfn "%d"
sumString "//;\n3;9;11" |> printfn "%d"

Some minor refactoring:

open System

let sumString (l:string) : int =
    let parseDelim (str:string) : char [] * string =
        match List.ofArray(str.ToCharArray()) with
            | '/'::'/'::c::'\n'::rest -> [|c|], String(Array.ofList rest)
            | _ -> [|','; '\n'|], str
    let (delims, toParse) = parseDelim l
    toParse.Split(delims)
        |> Array.map int
        |> Array.fold (+) 0

sumString "3,9,11" |> printfn "%d"
sumString "3\n9\n11" |> printfn "%d"
sumString "//;\n3;9;11" |> printfn "%d"

Not sure it's worth the conversion to char list to use pattern matching.
Parser combinators are more fun. :)

Disclaimer: F# newbie

Thanks Dave. I learned two things:

• String(Array.ofList rest) - didn't know about String
• Array.fold (+) 0 - obvious in hindsight :P