Fixed some longstanding issues regarding constraints on type constructors.

Now constraints on type constructors are checked correctly when
checking that types are well formed using Env.wf_typ. The arity and
kind of type constructor arguments are also checked in the same way.

Also some general cleanups to the type checker code, with some
auxillary functions being moved to more appropriate files.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/util.ml b/src/util.ml
index 762e0f88..4f7878c7 100644
--- a/src/util.ml
+++ b/src/util.ml
@@ -365,3 +365,8 @@ let is_some = function
   | None -> false
 
 let is_none opt = not (is_some opt)
+
+let rec take n xs = match n, xs with
+  | 0, _ -> []
+  | n, [] -> []
+  | n, (x :: xs) -> x :: take (n - 1) xs