TDNR seems to work!

parser-typechecker/src/Unison/Typechecker.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE OverloadedLists #-}
@@ -167,13 +168,14 @@ typeDirectedNameResolution resultSoFar env = do
     Typechecking (Context.Note (Context.SolvedBlank (B.Resolve loc n) _ it) _)
       -> do
         suggestions <-
-          State.lift
+          fmap join
+          . State.lift
           . traverse (resolve it)
           . join
           . maybeToList
           . Map.lookup (Text.pack n)
           $ terms env
-        suggestOrReplace loc (Text.pack n) it (join suggestions)
+        suggestOrReplace loc (Text.pack n) it suggestions
     _ -> pure ()
  where
   suggestOrReplace

parser-typechecker/tests/Unison/Test/Typechecker.hs

@@ -4,20 +4,19 @@
 
 module Unison.Test.Typechecker where
 
-import           EasyTest
-
 import           Control.Monad          (join, void)
 import           Control.Monad.IO.Class (liftIO)
 import           Data.Foldable          (traverse_)
 import           Data.Text              (unpack)
 import           Data.Text.IO           (readFile)
+import           EasyTest
 import           System.FilePath        (joinPath, splitPath)
 import           System.FilePath.Find   (always, extension, find, (==?))
 import           Unison.FileParsers     (Type, Term, parseAndSynthesizeAsFile)
 import           Unison.Parser          as Parser
 import qualified Unison.PrintError      as PrintError
-import qualified Unison.Result          as Result
 import           Unison.Result          (Result(..))
+import qualified Unison.Result          as Result
 import           Unison.Symbol          (Symbol)
 import           Unison.Util.Monoid     (intercalateMap)
 

unison-src/tests/tdnr.u

@@ -1,6 +1,6 @@
 -- Should resolve + with Type-directeded name resolution
 
-x :: UInt64
+x : UInt64
 x = 4 + 2
 
 x