1 files changed, 82 insertions, 0 deletions
diff --git a/src/Data/Array/Nested/Trace/TH.hs b/src/Data/Array/Nested/Trace/TH.hs
new file mode 100644
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+++ b/src/Data/Array/Nested/Trace/TH.hs
@@ -0,0 +1,82 @@
+{-# LANGUAGE ImportQualifiedPost #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE TemplateHaskellQuotes #-}
+module Data.Array.Nested.Trace.TH where
+
+import Control.Monad (zipWithM)
+import Data.List (foldl', intersperse)
+import Data.Maybe (isJust)
+import Language.Haskell.TH hiding (cxt)
+
+import Debug.Trace qualified as Debug
+
+import Data.Array.Mixed.Types
+import Data.Array.Nested
+
+
+splitFunTy :: Type -> ([TyVarBndr Specificity], Cxt, [Type], Type)
+splitFunTy = \case
+  ArrowT `AppT` t1 `AppT` t2 ->
+    let (vars, cx, args, ret) = splitFunTy t2
+    in (vars, cx, t1 : args, ret)
+  ForallT vs cx' t ->
+    let (vars, cx, args, ret) = splitFunTy t
+    in (vars ++ vs, cx ++ cx', args, ret)
+  t -> ([], [], [], t)
+
+data Relevant = RRanked Type Type
+              | RShaped Type Type
+              | RMixed Type Type
+              | RShowable Type
+  deriving (Show)
+
+-- | If so, returns the element type
+isRelevant :: Type -> Maybe Relevant
+isRelevant (ConT name `AppT` sht `AppT` ty)
+  | name == ''Ranked = Just (RRanked sht ty)
+  | name == ''Shaped = Just (RShaped sht ty)
+  | name == ''Mixed = Just (RMixed sht ty)
+isRelevant ty@(ConT name `AppT` _)
+  | name `elem` [''IShR, ''IIxR, ''ShS, ''IIxS, ''SNat] =
+      Just (RShowable ty)
+isRelevant _ = Nothing
+
+convertType :: Type -> Q (Type, [Bool], Bool)
+convertType typ =
+  let (tybndrs, cxt, args, ret) = splitFunTy typ
+      argrels = map isRelevant args
+      retrel = isRelevant ret
+
+      showhead (RRanked n ty) = [ConT ''Mixed `AppT` (ConT ''Replicate `AppT` n `AppT` ConT 'Nothing) `AppT` ty]
+      showhead (RShaped sh ty) = [ConT ''Mixed `AppT` (ConT ''MapJust `AppT` sh) `AppT` ty]
+      showhead (RMixed sh ty) = [ConT ''Mixed `AppT` sh `AppT` ty]
+      showhead (RShowable _) = []
+  in return
+      (ForallT tybndrs
+               (cxt ++ [ConT ''Show `AppT` hd
+                       | Just rel <- retrel : argrels
+                       , hd <- showhead rel])
+               (foldr (\a b -> ArrowT `AppT` a `AppT` b) ret args)
+      ,map isJust argrels
+      ,isJust retrel)
+
+convertFun :: Name -> Q [Dec]
+convertFun funname = do
+  defname <- newName (nameBase funname)
+  (convty, argarrs, retarr) <- reifyType funname >>= convertType
+  names <- zipWithM (\b i -> newName ((if b then "t" else "x") ++ show i)) argarrs [1::Int ..]
+  resname <- newName "res"
+  let tracenames = map fst (filter snd (zip (names ++ [resname]) (argarrs ++ [retarr])))
+  let ex = LetE [ValD (VarP resname)
+                      (NormalB (foldl' AppE (VarE funname) (map VarE names)))
+                      []]
+                (VarE 'Debug.trace
+                  `AppE` (VarE 'concat `AppE` ListE
+                            ([LitE (StringL ("oxtrace: " ++ nameBase funname ++ " ["))] ++
+                             intersperse (LitE (StringL ", "))
+                                         (map (\n -> VarE 'show `AppE` VarE n) tracenames) ++
+                             [LitE (StringL "]")]))
+                  `AppE` VarE resname)
+  return
+    [SigD defname convty
+    ,FunD defname [Clause (map VarP names) (NormalB ex) []]]