Backport export of NonEmpty

Backport of #11761

changelog_begin
changelog_end

compiler/damlc/daml-stdlib-src/DA/NonEmpty.daml

@@ -22,6 +22,7 @@ module DA.NonEmpty
   , reverse
   , find
   , delete
+  , deleteBy
   , foldl1
   , foldr1
   , foldr
@@ -115,13 +116,7 @@ find p (NonEmpty head tail)
 -- | The 'deleteBy' function behaves like 'delete', but takes a
 -- user-supplied equality predicate.
 deleteBy : (a -> a -> Bool) -> a -> NonEmpty a -> [a]
-deleteBy eq a n@(NonEmpty head [])
-  | head `eq` a = []
-  | otherwise   = [head]
-deleteBy eq a (NonEmpty head (t::ts))
-  | head `eq` a = t::ts
-  | t `eq` a    = head::ts
-  | otherwise   = head :: t :: L.deleteBy eq a ts
+deleteBy eq a ts = L.deleteBy eq a (toList ts)
 
 -- | Remove the first occurence of x from the non-empty list, potentially
 -- removing all elements.

compiler/damlc/tests/daml-test-files/NonEmpty.daml

@@ -46,3 +46,11 @@ testDelete = scenario do
   delete 1 (NonEmpty 0 [2, 1]) === [0, 2]
   delete 1 (NonEmpty 0 [1, 2, 1]) === [0, 2, 1]
 
+
+testDeleteBy = scenario do
+    deleteBy eq 1 (NonEmpty 0 []) === [0]
+    deleteBy eq 1 (NonEmpty 1 []) === []
+    deleteBy (/=) 1 (NonEmpty 0 [1]) === [1]
+  where
+    -- Get dlint to stop complaining.
+    eq = (==)