Adding arbitrary key=value pairs to the FAKE script

README.md

fake build -t all --env a=b --env c=d --env e=f

*** [Env ("a","b"); Env ("c","d"); Env ("e","f")]

build.fsx

open Argu
type EnvVars = | [<EqualsAssignment>] Env of key:string * value:string
with 
    interface IArgParserTemplate with
        member __.Usage = ""

let parser = ArgumentParser.Create<EnvVars>()
let results = parser.ParseCommandLine(System.Environment.GetCommandLineArgs(), true, true, false)
printfn "*** %A" (results.GetAllResults())

// ...

Target.runOrDefaultWithArguments "All"