recToList

2 files changed, 8 insertions, 0 deletions

diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index d0c2e7a1..32a9679c 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -353,3 +353,7 @@ fun assocAdd [a] [b] (_ : eq a) (x : a) (y : b) (ls : t (a * b)) =
     case assoc x ls of
         None => (x, y) :: ls
       | Some _ => ls
+
+fun recToList [a ::: Type] [r ::: {Unit}] (fl : folder r)
+  = @foldUR [a] [fn _ => list a] (fn [nm ::_] [rest ::_] [[nm] ~ rest] x xs =>
+				      x :: xs) [] fl
diff --git a/lib/ur/list.urs b/lib/ur/list.urs
index 8284510d..dc8fdeba 100644
--- a/lib/ur/list.urs
+++ b/lib/ur/list.urs
@@ -79,3 +79,7 @@ val replaceNth : a ::: Type -> list a -> int -> a -> list a
 val assoc : a ::: Type -> b ::: Type -> eq a -> a -> t (a * b) -> option b
 
 val assocAdd : a ::: Type -> b ::: Type -> eq a -> a -> b -> t (a * b) -> t (a * b)
+
+(** Converting records to lists *)
+
+val recToList : a ::: Type -> r ::: {Unit} -> folder r -> $(mapU a r) -> t a