adding Iso optic for MStruct

Author: bbarker

Foreign/Matlab/Array/IMX.hs

@@ -154,8 +154,8 @@ imxData a = do
   imxc MXClassStruct False      = do
     s <- mxArraySize a'
     fv <- mxArrayGetAll a'
-    f <- if null fv then mStructFields a' else return (map fst (DM.toList $ mStruct (head fv)))
-    listIMXStruct f s =.< mapM imxData (concatMap (map snd . DM.toList . mStruct) fv)
+    f <- if null fv then mStructFields a' else return (map fst (DM.toList $ _mStruct (head fv)))
+    listIMXStruct f s =.< mapM imxData (concatMap (map snd . DM.toList . _mStruct) fv)
   imxc MXClassLogical False     = IMXLogical    =.< imxa return
   imxc MXClassChar False        = IMXChar       =.< imxa return
   imxc MXClassDouble False      = IMXDouble     =.< imxa return

Foreign/Matlab/Internal.hsc

@@ -1,3 +1,7 @@
+{-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
 module Foreign.Matlab.Internal (
     CBool, boolC, cBool,
     MIO,
@@ -22,12 +26,17 @@ module Foreign.Matlab.Internal (
     MAny, MAnyArray,
     MNull, mNullArray, isMNull,
     MCell(..),
-    MStruct(..),
+    MStruct(..), mStruct,
     MXFun, MFun,
     MWSize, MWIndex, MWSignedIndex
   ) where
 
+import           Data.Coerce (Coercible, coerce)
 import qualified Data.Map.Strict as DM
+import           Data.Profunctor
+import           Data.Profunctor.Unsafe
+
+
 import           Foreign
 import           Foreign.C.Types
 import qualified Data.Char
@@ -37,7 +46,23 @@ import           Foreign.Matlab.Util
 
 type MIO a = IO a
 
--- type CBool = #type bool
+
+-- Lens types copied in --
+
+type Iso s t a b = forall p f. (Profunctor p, Functor f) => p a (f b) -> p s (f t)
+type Iso' s a = Iso s s a a
+
+coerce' :: forall a b. Coercible a b => b -> a
+coerce' = coerce (id :: a -> a)
+{-# INLINE coerce' #-}
+
+coerced :: forall s t a b. (Coercible s a, Coercible t b) => Iso s t a b
+# if __GLASGOW_HASKELL__ >= 710
+coerced l = rmap (fmap coerce') l .# coerce
+# else
+coerced l = case sym Coercion :: Coercion a s of
+              Coercion -> rmap (fmap coerce') l .# coerce
+# endif
 
 boolC :: CBool -> Bool
 boolC = (0 /=)
@@ -194,12 +219,15 @@ instance MType MCell MCell where
   mxClassOf _ = MXClassCell
 
 -- |A single struct in an array, represented by an (ordered) list of key-value pairs
-newtype MStruct = MStruct { mStruct :: DM.Map String MAnyArray }
+newtype MStruct = MStruct { _mStruct :: DM.Map String MAnyArray }
 instance MType MStruct MStruct where
   hs2mx = id
   mx2hs = id
   mxClassOf _ = MXClassStruct
 
+mStruct :: Iso' MStruct (DM.Map String MAnyArray)
+mStruct = coerced
+
 type MXFun = CInt -> Ptr MXArrayPtr -> CInt -> Ptr MXArrayPtr -> IO ()
 -- |A Matlab function
 type MFun =

matlab.cabal

@@ -42,6 +42,7 @@ library
                       array,
                       filepath,
                       path,
+		      profunctors >= 5.3,
                       Cabal < 3.0
   Exposed-modules:    Foreign.Matlab,
                       Foreign.Matlab.Types,