Yargs from Fable

App.fs

module App

// a port of the last example: Yargs is here to help you...
// https://github.com/yargs/yargs/blob/master/docs/examples.md#yargs-is-here-to-help-you
// It could the number of lines in a file.

open Yargs
open Fable.Core
open System.Text.RegularExpressions

let argv =
    yargs
        .usage("Usage: $0 <command> [options]")
        .command(U2.Case1 "count", "Count the lines in a file")
        .example("$0 count -f foo.js", "count the lines in the given file")
        .alias("f", U2.Case1 "file")
        .nargs("f", 1.)
        .describe(U2.Case1 "f", "Load a file")
        .demandOption(U2.Case1 "f", "Please specify a file.")
        .help("h")
        .alias("h", U2.Case1 "help")
        .epilog("copyright 2015")
        .argv

let s = Node.fs.createReadStream(PathLike.ofString(argv.["file"].Value :?> string))

let mutable lines = 1

s.on_data(fun buf ->
    let s = 
        match buf with
        | U2.Case1 b -> b.toString()
        | U2.Case2 s -> s
    lines <- lines + Regex.Matches(s, "(\n)").Count
) |> ignore

s.on_end(fun _ ->
    printfn "%d" lines
) |> ignore

SimpleExample.fs

open Yargs
open Fable.Import.JS

let argv = yargs.argv

let retreat() = printfn "Retreat from the xupptumblers!"
let plunder() = printfn "Plunder more riffiwobbles!"

match argv.Item "ships", argv.Item "distance" with
| Some ships, Some distance ->
    let ships = parseFloat (ships :?> string)
    let distance = parseFloat (distance :?> string)
    if isNaN ships || isNaN distance then
        retreat()
    else
        if ships > 3. && distance < 53.5 then
            plunder()
        else
            retreat()
| _ -> retreat()

started.txt

dotnet new -i ctaggart.templates
dotnet new --list -lang f#
dotnet new yargs -n myconsoleapp
cd myconsoleapp
.\build.ps1
.\start.ps1

ts2fable-yargs.fs

    let argv =
        yargs
            .usage("Usage: ts2fable some.d.ts src/Some.fs")
            .command(U2.Case1 "$0 [files..]", "")
            .demandOption(U2.Case1 "files", "")
            .help()
            .argv

    let files = argv.["files"].Value :?> string array |> List.ofArray
    let tsfiles = files |> List.filter (fun s -> s.EndsWith ".ts")
    let fsfile = files |> List.tryFind (fun s -> s.EndsWith ".fs")
    
    match tsfiles.Length, fsfile with
    | 0, _ -> failwithf "Please provide the path to a TypeScript file"
    | _, None -> failwithf "Please provide the path to the F# file to be written "
    | _, Some fsf ->
        printfn "ts2fable %s" Version.version

        // validate ts files exist
        for ts in tsfiles do
            if fs.existsSync(PathLike.ofString ts) = false then
                failwithf "TypeScript file not found: %s" ts

        writeFile tsfiles fsf