ENH clean up errors in ops

lib/Internal/Database/Ops.hs

@@ -31,6 +31,7 @@ import RIO hiding (LogFunc, isNothing, on, (^.))
 import RIO.List ((\\))
 import qualified RIO.List as L
 import qualified RIO.Map as M
+import qualified RIO.NonEmpty as N
 import qualified RIO.Text as T
 
 migrate_
@@ -243,13 +244,13 @@ paths2IDs =
     . L.sortOn fst
     . fmap (first pathList)
   where
-    pathList (AcntPath t ns) = reverse $ atName t : ns
+    pathList (AcntPath t []) = atName t :| []
+    pathList (AcntPath t ns) = N.reverse $ atName t :| ns
 
-trimNames :: [[T.Text]] -> [AcntID]
-trimNames = fmap fmt . trimAll 0
+-- none of these errors should fire assuming that input is sorted and unique
+trimNames :: [N.NonEmpty T.Text] -> [AcntID]
+trimNames = fmap (T.intercalate "_" . reverse) . trimAll 0
   where
-    fmt [] = err "blank path"
-    fmt ys = T.intercalate "_" $ reverse ys
     trimAll _ [] = []
     trimAll i (y : ys) = case L.foldl' (matchPre i) (y, [], []) ys of
       (a, [], bs) -> reverse $ trim i a : bs
@@ -268,10 +269,10 @@ trimNames = fmap fmt . trimAll 0
                   [] -> [trim i y]
                   _ -> trimAll (i + 1) (reverse $ y : ys)
              in (new, [], reverse next ++ old)
-    trim i = take (i + 1)
+    trim i = N.take (i + 1)
     err msg = errorWithoutStackTrace $ "Import.Database.Ops.hs: " ++ msg
 
-(!?) :: [a] -> Int -> Maybe a
+(!?) :: N.NonEmpty a -> Int -> Maybe a
 xs !? n
   | n < 0 = Nothing
   -- Definition adapted from GHC.List