dragList almost kinda works

2 files changed, 12 insertions, 0 deletions

diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index 3d4134ea..9e2550ca 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -44,6 +44,16 @@ fun foldlAbort [a] [b] f =
         foldlAbort'
     end
 
+val length = fn [a] =>
+                let
+                    fun length' acc (ls : list a) =
+                        case ls of
+                            [] => acc
+                          | _ :: ls => length' (acc + 1) ls
+                in
+                    length' 0
+                end
+
 val rev = fn [a] =>
              let
                  fun rev' acc (ls : list a) =
diff --git a/lib/ur/list.urs b/lib/ur/list.urs
index ece85e8c..df1c8a52 100644
--- a/lib/ur/list.urs
+++ b/lib/ur/list.urs
@@ -8,6 +8,8 @@ val foldlAbort : a ::: Type -> b ::: Type -> (a -> b -> option b) -> b -> t a ->
 val foldlMapAbort : a ::: Type -> b ::: Type -> c ::: Type
                     -> (a -> b -> option (c * b)) -> b -> t a -> option (t c * b)
 
+val length : a ::: Type -> t a -> int
+
 val rev : a ::: Type -> t a -> t a
 
 val revAppend : a ::: Type -> t a -> t a -> t a