Provide ix*FromLinear for all three shape kinds

This speeds up {r,s}generatePrim

1 files changed, 7 insertions, 27 deletions

diff --git a/src/Data/Array/Nested/Mixed/Shape.hs b/src/Data/Array/Nested/Mixed/Shape.hs
index 8aa5a77..5a45a09 100644
--- a/src/Data/Array/Nested/Mixed/Shape.hs
+++ b/src/Data/Array/Nested/Mixed/Shape.hs
@@ -16,6 +16,7 @@
 {-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE StandaloneKindSignatures #-}
 {-# LANGUAGE StrictData #-}
+{-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE TypeOperators #-}
@@ -44,6 +45,7 @@ import GHC.TypeLits
 import GHC.TypeLits.Orphans ()
 #endif
 
+import Data.Array.Nested.Mixed.Shape.Internal
 import Data.Array.Nested.Types
 
 
@@ -276,33 +278,6 @@ ixxZipWith :: (i -> j -> k) -> IxX sh i -> IxX sh j -> IxX sh k
 ixxZipWith _ ZIX ZIX = ZIX
 ixxZipWith f (i :.% is) (j :.% js) = f i j :.% ixxZipWith f is js
 
-{-# INLINEABLE ixxFromLinear #-}
-ixxFromLinear :: Num i => IShX sh -> Int -> IxX sh i
-ixxFromLinear = \sh ->  -- give this function arity 1 so that suffixes is shared when it's called many times
-  let suffixes = drop 1 (scanr (*) 1 (shxToList sh))
-  in \i ->
-      if i < 0 then outrange sh i else
-      case (sh, suffixes) of  -- unfold first iteration of fromLin to do the range check
-        (ZSX, _) | i > 0 -> outrange sh i
-                 | otherwise -> ZIX
-        (n :$% sh', suff : suffs) ->
-          let (q, r) = i `quotRem` suff
-          in if q >= fromSMayNat' n then outrange sh i else
-             fromIntegral q :.% fromLin sh' suffs r
-        _ -> error "impossible"
-  where
-    fromLin :: Num i => IShX sh -> [Int] -> Int -> IxX sh i
-    fromLin ZSX _ !_ = ZIX
-    fromLin (_ :$% sh') (suff : suffs) i =
-      let (q, r) = i `quotRem` suff  -- suff == shrSize sh'
-      in fromIntegral q :.% fromLin sh' suffs r
-    fromLin _ _ _ = error "impossible"
-
-    {-# NOINLINE outrange #-}
-    outrange :: IShX sh -> Int -> a
-    outrange sh i = error $ "ixxFromLinear: out of range (" ++ show i ++
-                            " in array of shape " ++ show sh ++ ")"
-
 ixxToLinear :: IShX sh -> IIxX sh -> Int
 ixxToLinear = \sh i -> fst (go sh i)
   where
@@ -684,3 +659,8 @@ instance KnownShX sh => IsList (ShX sh Int) where
   type Item (ShX sh Int) = Int
   fromList = shxFromList (knownShX @sh)
   toList = shxToList
+
+-- This needs to be at the bottom of the file to not split the file into
+-- pieces; some of the shape/index stuff refers to StaticShX.
+$(ixFromLinearStub "ixxFromLinear" [t| IShX |] [t| IxX |] [p| ZSX |] (\a b -> [p| (fromSMayNat' -> $a) :$% $b |]) [| ZIX |] [| (:.%) |] [| shxToList |])
+{-# INLINEABLE ixxFromLinear #-}