Add a fallback term constructor for other languages.

src/Language.hs

@@ -1,6 +1,13 @@
+{-# LANGUAGE DataKinds #-}
 module Language where
 
+import Data.Record
+import Info
 import Prologue
+import Source
+import SourceSpan
+import qualified Syntax as S
+import Term
 
 -- | A programming language.
 data Language =
@@ -30,3 +37,17 @@ languageForType mediaType = case mediaType of
     ".js" -> Just JavaScript
     ".rb" -> Just Ruby
     _ -> Nothing
+
+termConstructor
+  :: Source Char -- ^ The source that the term occurs within.
+  -> IO SourceSpan -- ^ The span that the term occupies. This is passed in 'IO' to guarantee some access constraints & encourage its use only when needed (improving performance).
+  -> Text -- ^ The name of the production for this node.
+  -> Range -- ^ The character range that the term occupies.
+  -> [Term Text (Record '[Range, Category])] -- ^ The child nodes of the term.
+  -> IO (Term Text (Record '[Range, Category])) -- ^ The resulting term, in IO.
+termConstructor source sourceSpan name range children
+  | name == "ERROR" = sourceSpan >>= withDefaultInfo . (`S.Error` children)
+  | otherwise = withDefaultInfo $ case (name, children) of
+  (_, []) -> S.Leaf . toText $ slice range source
+  _ -> S.Indexed children
+  where withDefaultInfo syntax = pure $! cofree ((range .: Other name .: RNil) :< syntax)

src/TreeSitter.hs

@@ -55,4 +55,4 @@ documentToTerm language document blob = alloca $ \ root -> do
         termConstructor = case language of
           JavaScript -> JS.termConstructor
           C -> C.termConstructor
-          _ -> JS.termConstructor
+          _ -> Language.termConstructor