Сlient: introduce File type

Introduce File type that checks existence of file on creation
and is used in FSharpLintExecutableFile instead of string path.

Author: webwarrior-ws

src/FSharpLint.Client/FSharpLintToolLocator.fs

@@ -141,10 +141,11 @@ let private fsharpLintVersionOnPath () : (FSharpLintExecutableFile * FSharpLintV
                 if File.Exists fsharpLint then Some fsharpLint
                 else None)
         |> Seq.tryHead
+        |> Option.bind File.From
 
     fsharpLintExecutableOnPathOpt
     |> Option.bind (fun fsharpLintExecutablePath ->
-        let processStart = ProcessStartInfo(fsharpLintExecutablePath)
+        let processStart = ProcessStartInfo(File.Unwrap fsharpLintExecutablePath)
         processStart.Arguments <- "--version"
         processStart.RedirectStandardOutput <- true
         processStart.CreateNoWindow <- true
@@ -210,7 +211,7 @@ let createFor (startInfo: FSharpLintToolStartInfo) : Result<RunningFSharpLintToo
             ps.Arguments <- "--daemon"
             ps
         | FSharpLintToolStartInfo.ToolOnPath(FSharpLintExecutableFile executableFile) ->
-            let ps = ProcessStartInfo(executableFile)
+            let ps = ProcessStartInfo(File.Unwrap executableFile)
             ps.Arguments <- "--daemon"
             ps
 

src/FSharpLint.Client/LSPFSharpLintServiceTypes.fs

@@ -13,8 +13,18 @@ type FSharpLintResponseCode =
     | ErrDaemonCreationFailed = -1
     | OkCurrentDaemonVersion = 0
 
+type File = private File of string 
+with 
+    static member From (filePath: string) =
+        if File.Exists(filePath) then
+            filePath |> File |> Some
+        else
+            None
+
+    static member Unwrap(File f) = f
+
 type FSharpLintVersion = FSharpLintVersion of string
-type FSharpLintExecutableFile = FSharpLintExecutableFile of string
+type FSharpLintExecutableFile = FSharpLintExecutableFile of File
 type Folder = private Folder of string 
 with 
     static member from (filePath: string) =

src/FSharpLint.Client/LSPFSharpLintServiceTypes.fsi

@@ -8,9 +8,14 @@ type FSharpLintResponseCode =
     | ErrDaemonCreationFailed = -1
     | OkCurrentDaemonVersion = 0
 
+type File = private File of string
+with
+    static member From: string -> File option
+    static member Unwrap: File -> string
+
 type FSharpLintVersion = FSharpLintVersion of string
 
-type FSharpLintExecutableFile = FSharpLintExecutableFile of string
+type FSharpLintExecutableFile = FSharpLintExecutableFile of File
 
 type Folder = private Folder of string
 with