F#で文字列をeval ちょっと修正版

Program.fs

open Microsoft.FSharp.Compiler.CodeDom
open System.Reflection
open System.CodeDom.Compiler

type EvalResult<'a> =
| CompileError of CompilerError seq
| RuntimeError of exn
| Success of 'a

let eval args expr =
  use provider = new FSharpCodeProvider()
  let src = "module Temp\n\
             let body args =\n  " + expr
  let param = CompilerParameters(GenerateInMemory=true)
  let res = provider.CompileAssemblyFromSource(param, src)
  let errors = res.Errors |> Seq.cast<CompilerError>
  if not(Seq.isEmpty errors) then
    CompileError errors
  else
    let asm = res.CompiledAssembly
    let t = asm.GetType("Temp")
    let m = t.GetMethod("body")
    try
      Success(m.Invoke(null, args |> List.toArray) :?> 'a)
    with
      e -> RuntimeError e

[<EntryPoint>]
let main _ =
  match @"failwithf ""%s world!"" args" |> eval [ "hoge" ] with
  | Success _ -> printfn "success!"
  | _ -> printfn "oops..."
  0