Simple F# program to rename my C# test fixture methods

RenameFixtureMethods.fs

(*
  Description: Simple program to change naming conventions of my C# test fixtures.
  Purpose:     Learn F#!
  Author:      Giacomo Stelluti Scala
  Created:     2013-01-28
*)
open System
open System.IO
open System.Globalization
open System.Text

let readLines path =
    File.ReadAllLines(path)

let isUppercase (c:char) =
    let cat = Char.GetUnicodeCategory(c)
    if cat = UnicodeCategory.UppercaseLetter then
        true
    else
        false

let changeLine (line:string) =
    let parts = line.Split( [|" "|], StringSplitOptions.RemoveEmptyEntries)
    if parts.Length >= 2 &&
       String.CompareOrdinal(parts.[0], "public") = 0 &&
       String.CompareOrdinal(parts.[1], "void") = 0 then
        let newName = seq { for c in parts.[2] do
                                if isUppercase(c) then
                                    yield "_" + c.ToString().ToLowerInvariant()
                                else
                                    yield c.ToString() }
        let interm = newName |> Seq.reduce (+)
        let newMethod = interm.[1].ToString().ToUpperInvariant() + interm.Substring(2, interm.Length - 2)
        line.Replace(parts.[2], newMethod)
    else
        line

[<EntryPoint>]
let main argv = 
    if argv.Length <> 1 then
        printfn "Usage: RenameMethods [CSHARPFILE] >[NEW-CSHARPFILE]"
        1
    else
        let lines = readLines argv.[0]
        let mutable canChange = false
        let buffer = new StringBuilder()
        for line in lines do
            if line.Contains("[Fact]") then
                canChange <- true
                ignore(buffer.AppendLine(line))
            else
                if canChange = true then
                    canChange <- false
                    ignore(buffer.AppendLine(changeLine(line)))
                else
                    ignore(buffer.AppendLine(line))
        let str = buffer.ToString()
        printfn "%s" str
        0