Generic build script using Fake

I have something like a generic build script for a group of projects. I am using Fake but my F# skills are pretty bad. Would you please take a look and point where I can improve it?

ORIGINAL

```
#I @"./bin/tools/FAKE/tools/"
#r @"./bin/tools/FAKE/tools/FakeLib.dll"

open System
open System.IO
open Fake
open Fake.Git
open Fake.FSharpFormatting
open Fake.AssemblyInfoFile
open Fake.ReleaseNotesHelper

type System.String with member x.contains (comp:System.StringComparison) str = x.IndexOf(str,comp) >= 0

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// BEGIN EDIT

let appName = getBuildParamOrDefault "appName" ""
let appType = getBuildParamOrDefault "appType" ""
let appSummary = getBuildParamOrDefault "appSummary" ""
let appDescription = getBuildParamOrDefault "appDescription" ""
let appAuthors = ["YourNameHere";]

// END EDIT
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

let buildDir = @"./bin/Release" @@ appName
let releaseNotes = @"./src/" @@ appName @@ @"RELEASE_NOTES.md"
let release = LoadReleaseNotes releaseNotes

let nuget = environVar "NUGET"
let nugetOutDir = "./bin/nuget" @@ appName

Target "Clean" (fun _ -> CleanDirs [buildDir; nugetOutDir;])

Target "RestorePackages" (fun _ ->
let packagesDir = @"./src/packages"
!! "./**/packages.config"
|> Seq.iter (RestorePackage (fun p ->
{ p with
ToolPath = nuget
OutputPath = packagesDir }))
)

Target "Build" (fun _ ->
let appProjectFile = match appType with
| t when t = "msi" -> @"./src/" @@ appName + ".sln"
| _ -> @"./src/" @@ appName @@ appName + ".csproj"

!! appProjectFile
|> MSBuildRelease buildDir "Build"
|> Log "Build-Output: "
)

Target "CreateNuGet" (fun _ ->
let packages = [appName, appType]
for appName,appType in packages do

All of the match expressions can be simplified. For example,

match fileExists nugetPackagesFile with
| t when t = true -> ...
| _ -> ...

Can be

match fileExists nugetPackagesFile with
| true -> ...
| _ -> ...

Similarly,

match appType with
 | t when t = "web" -> ...
 | t when t = "nuget" -> ...
 | _ -> ...

Can be

match appType with
  | "web" -> ...
  | "nuget" -> ...
  | _ -> ...

In the first example above, fun(A,B) -> A can be written as fst.

It looks like nugetDependenciesFlat is only used by exclude, where you're already appending "CodeContracts". So you can change the second match in nugetDependenciesFlat from _ -> ["CodeContracts"] to _ -> [].

While you're at it, change nugetDependenciesFlat @ ["CodeContracts"] to "CodeContracts" :: nugetDependenciesFlat. The reason being, prepending an element to a list is a constant-time operation, while appending will take time proportional to to the length of nugetDependenciesFlat. It won't make a noticeable difference since I assume nugetDependenciesFlat will be very short, but it's a good practice to get into.

StackExchange Code Review Q#82517, answer score: 6