Defer pattern-matching exhaustiveness checks and normalize pattern types more thoroughly

2 files changed, 17 insertions, 1 deletions

diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index 8493f2f5..0776ff30 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -74,6 +74,19 @@ fun mapM [m ::: (Type -> Type)] (_ : monad m) [a] [b] f =
         mapM' []
     end
 
+fun mapXM [m ::: (Type -> Type)] (_ : monad m) [a] [ctx ::: {Unit}] f =
+    let
+        fun mapXM' ls =
+            case ls of
+                [] => return <xml/>
+              | x :: ls =>
+                this <- f x;
+                rest <- mapXM' ls;
+                return <xml>{this}{rest}</xml>
+    in
+        mapXM'
+    end
+
 fun filter [a] f =
     let
         fun fil acc ls =
diff --git a/lib/ur/list.urs b/lib/ur/list.urs
index 28f08317..92589508 100644
--- a/lib/ur/list.urs
+++ b/lib/ur/list.urs
@@ -15,7 +15,10 @@ val mapPartial : a ::: Type -> b ::: Type -> (a -> option b) -> t a -> t b
 val mapX : a ::: Type -> ctx ::: {Unit} -> (a -> xml ctx [] []) -> t a -> xml ctx [] []
 
 val mapM : m ::: (Type -> Type) -> monad m -> a ::: Type -> b ::: Type
-           -> (a -> m b) -> list a -> m (list b)
+           -> (a -> m b) -> t a -> m (t b)
+
+val mapXM : m ::: (Type -> Type) -> monad m -> a ::: Type -> ctx ::: {Unit}
+            -> (a -> m (xml ctx [] [])) -> t a -> m (xml ctx [] [])
 
 val filter : a ::: Type -> (a -> bool) -> t a -> t a