prefer full .NET Frameworks over PCL, even if older

See @cdrnet's comments on fsprojects#380.

src/Paket.Core/PlatformMatching.fs

@@ -36,25 +36,41 @@ let getPenalty (requiredPlatforms:FrameworkIdentifier list) (path:string) =
     requiredPlatforms
     |> List.sumBy (getPathPenalty path)
 
+type PathPenalty = (string * int)
+
+let comparePaths (p1 : PathPenalty) (p2 : PathPenalty) =
+    let platformCount1 = (extractPlatforms (fst p1)).Length
+    let platformCount2 = (extractPlatforms (fst p2)).Length
+
+    // prefer full framwork over portable
+    if platformCount1 = 1 && platformCount2 > 1 then
+        -1
+    else if platformCount1 > 1 && platformCount2 = 1 then
+        1
+    // prefer lower version penalty
+    else if snd p1 < snd p2 then
+       -1
+    else if snd p1 > snd p2 then
+       1
+    // prefer portable platform whith less platforms
+    else if platformCount1 < platformCount2 then
+        -1
+    else if platformCount1 > platformCount2 then
+        1
+    else
+        0
+
 let findBestMatch (paths : string list) (targetProfile : TargetProfile) = 
     let requiredPlatforms = 
         match targetProfile with
         | PortableProfile(_, platforms) -> platforms
         | SinglePlatform(platform) -> [ platform ]
 
-    let pathPenalties = 
-        paths 
-        |> List.map (fun path -> (path, getPenalty requiredPlatforms path))
-
-    let minPenalty = 
-        pathPenalties
-        |> Seq.map snd
-        |> Seq.min
-
-    pathPenalties
-    |> Seq.filter (fun (path, penalty) -> penalty = minPenalty && minPenalty < maxPenalty)
+    paths 
+    |> List.map (fun path -> path, (getPenalty requiredPlatforms path))
+    |> List.filter (fun (_, penalty) -> penalty < maxPenalty)
+    |> List.sortWith comparePaths
     |> Seq.map fst
-    |> Seq.sortBy (fun path -> (extractPlatforms path).Length)
     |> Seq.tryFind (fun _ -> true)
 
 // For a given list of paths and target profiles return tuples of paths with their supported target profiles.

tests/Paket.Tests/InstallModel/Penalty/PenaltySpecs.fs

@@ -67,7 +67,7 @@ module ``Given an empty path`` =
 
 module ``Given a list of paths`` = 
     let paths = 
-        [ "net40"; "net45"; "portable-monotouch+monoandroid"; "portable-net40+sl5+win8+wp8+wpa81"; 
+        [ "net40"; "portable-monotouch+monoandroid"; "portable-net40+sl5+win8+wp8+wpa81"; 
           "portable-net45+winrt45+wp8+wpa81"; "portable-win81+wpa81"; "portable-windows8+net45+wp8"; "sl5"; "win8"; 
           "wp8" ]
 
@@ -83,6 +83,10 @@ module ``Given a list of paths`` =
     let ``it should find no match for Silverlight 4``() = 
         findBestMatch paths (SinglePlatform(Silverlight "v4.0")) |> shouldEqual None
 
+    [<Test>]
+    let ``it should prefer (older) full .NET frameworks over portable class libraries``() = 
+        findBestMatch paths (SinglePlatform(DotNetFramework FrameworkVersion.V4_5)) |> shouldEqual (Some "net40")
+
     module ``when I get the supported target profiles`` = 
         let supportedTargetProfiles = getSupportedTargetProfiles paths