anchor.diff:  
   let check (file: string) =
       try
  -        let content =
  -            use file = new StreamReader(file)
  -            file.ReadToEnd()
  +        let content = System.IO.File.ReadAllText file
           if not (testCompile content) then
               printfn "Invalid input file '%s'" file
               false
  
positive.code:         printfn "%A" e
          false
  
  [<EntryPoint>]
  let main argv =
      initOpenTK()
      let mutable failures = 0
      let inputs = Directory.GetFiles("tests/unit", "*.frag")
      for f in inputs do
          if not (check f) then
              failures <- failures + 1
      if failures = 0 then
          printfn "All good."
          // System.Console.ReadLine() |> ignore
          0
      else
          printfn "%d failures." failures
          // System.Console.ReadLine() |> ignore
          1
  
negative.code: ﻿open OpenTK.Graphics.OpenGL
  open System
  open System.Diagnostics
  open System.IO
  
  let initOpenTK () =
  