diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # language-ats
 
+## 1.7.7.0
+
+  * Improved parse errors
+  * Add `getDependenciesC`
+
 ## 1.7.6.2
 
   * Fix bug in handling of char literals
diff --git a/language-ats.cabal b/language-ats.cabal
--- a/language-ats.cabal
+++ b/language-ats.cabal
@@ -1,6 +1,6 @@
 cabal-version:   1.18
 name:            language-ats
-version:         1.7.6.3
+version:         1.7.7.0
 license:         BSD3
 license-file:    LICENSE
 copyright:       Copyright: (c) 2018-2019 Vanessa McHale
diff --git a/src/Language/ATS.hs b/src/Language/ATS.hs
--- a/src/Language/ATS.hs
+++ b/src/Language/ATS.hs
@@ -14,6 +14,7 @@
                     , defaultFixityState
                     -- * Library functions
                     , getDependencies
+                    , getDependenciesC
                     -- * Syntax Tree
                     , ATS (..)
                     , Declaration (..)
@@ -67,7 +68,7 @@
 import           Control.Monad
 import           Control.Monad.IO.Class
 import           Control.Monad.Trans.State
-import           Data.Version (Version)
+import           Data.Version                 (Version)
 import           GHC.IO.Handle.FD             (stderr)
 import           Language.ATS.Lexer
 import           Language.ATS.Parser
@@ -76,7 +77,7 @@
 import           Language.ATS.Types
 import           Language.ATS.Types.Lens
 import           Lens.Micro
-import           Paths_language_ats (version)
+import           Paths_language_ats           (version)
 import           Text.PrettyPrint.ANSI.Leijen hiding ((<$>))
 
 -- | @since 1.7.4.0
@@ -126,5 +127,21 @@
 getDependencies (ATS ds) = g =<< ds
     where g (Load _ _ _ s)   = [s]
           g (Include s)      = [s]
-          g (Local _ as as') = foldMap getDependencies [as, as']
+          g (Local _ as as') = getDependencies =<< [as, as']
           g _                = mempty
+
+-- | Extract a list of @#include#-ed filepaths, plus all external C blocks.
+--
+-- @since 1.7.7.0
+getDependenciesC :: ATS a -> ([FilePath], [String])
+getDependenciesC (ATS ds) = go (d <$> ds)
+    where
+        d (Load _ _ _ s)   = ([s], [])
+        d (Include s)      = ([s], [])
+        d (Local _ as as') = appendBoth (getDependenciesC as) (getDependenciesC as')
+        d (CBlock str)     = ([],[str])
+        d _                = ([],[])
+        appendBoth :: ([a], [b]) -> ([a], [b]) -> ([a], [b])
+        appendBoth (x, y) (x', y') = (x ++ x', y ++ y')
+        go :: [([a], [b])] -> ([a], [b])
+        go xs = (concat (fst <$> xs), concat (snd <$> xs))
diff --git a/src/Language/ATS/Parser.y b/src/Language/ATS/Parser.y
--- a/src/Language/ATS/Parser.y
+++ b/src/Language/ATS/Parser.y
@@ -415,6 +415,7 @@
           | minus {% left $ Expected $1 "Arrow" "-" }
           | eq {% left $ Expected $1 "Arrow" "=" }
           | minus {% left $ Expected $1 "Arrow" "-" }
+          | customOperator {% left $ Expected (token_posn $1) "Arrow" ((\(Operator _ s) -> s) $1) }
           | CaseArrow vbar {% left $ Expected $2 "Expression" "|" }
 
 LambdaArrow :: { LambdaType AlexPosn }