subcommand-parser.fsx

#r "nuget: System.CommandLine, 	2.0.0-beta3.22106.2"

open System.CommandLine
open System.CommandLine.Builder
open System.CommandLine.Parsing
open System.CommandLine.Invocation
open System.Threading.Tasks
open System

let args = fsi.CommandLineArgs[1..]

let dummyProjectData = Map [
    "dummy",  Map [
        "name", "Dummy"
    ]
]

let rootCommand = RootCommand()
let projectCommand = Command("project", "Manage projects")
let projectArg = Argument<string>("project", "The project to build")
projectCommand.AddArgument(projectArg)

let setSubCommand = Command("set", "Set a configuration value")
let keyArg = Argument<string>("key", "The configuration key")
keyArg.Arity <- ArgumentArity.ExactlyOne

let valueArg = Argument<string>("value",  "The configuration value")
valueArg.Arity <- ArgumentArity.ZeroOrOne

setSubCommand.AddArgument(keyArg)
setSubCommand.AddArgument(valueArg)

setSubCommand.SetHandler(
    Func<_,_,_,_,_>(fun (project: string) (key: string) (value: string) (console: IConsole) -> 
        task {
            match value with
            | null ->
                console.WriteLine($"getting value for {key} from {project}")
                let v = 
                    dummyProjectData
                    |> Map.tryFind project
                    |> Option.bind (Map.tryFind key)
                match v with
                | None -> console.WriteLine("not found")
                | Some v -> console.WriteLine(v)
                return 0
                // get value for key
            | v -> 
                console.WriteLine($"setting {key} to {v} in {project}")
                return 0
        } :> Task
    ), projectArg, keyArg, valueArg)

projectCommand.AddCommand setSubCommand
rootCommand.AddCommand projectCommand

let parser = CommandLineBuilder(rootCommand).UseDefaults().Build()

let parse (args: string[]) = 
    parser.Parse(args)

let run (args: string[]) = 
    parser.Invoke(args)

> run [|"fsi";"project";"dummy";"set";"name";"not so dumb"|];;
setting name to not so dumb in dummy
val it: int = 0