added Has-classes and a lens for Engine and refactored optics

Author: bbarker

Foreign/Matlab/Engine.hsc

@@ -14,6 +14,7 @@ module Foreign.Matlab.Engine (
     EngineEvalArg(..),
     engineEvalFun,
     engineEvalProc,
+    HasEngine(..), SetEngine(..),
     qt
   ) where
 
@@ -23,6 +24,7 @@ import Foreign.C.String
 import Foreign.C.Types
 import Data.List
 import Foreign.Matlab.Array (createMXScalar)
+import Foreign.Matlab.Optics
 import Foreign.Matlab.Util
 import Foreign.Matlab.Internal
 
@@ -31,6 +33,16 @@ import Foreign.Matlab.Internal
 data EngineType
 type EnginePtr = Ptr EngineType
 
+
+class HasEngine env where
+  getEngine :: env -> Engine
+
+class HasEngine env => SetEngine env where
+  setEngine :: env -> Engine -> env
+
+  engine :: Lens' env Engine
+  engine = lens getEngine setEngine
+
 -- |A Matlab engine instance
 newtype Engine = Engine (ForeignPtr EngineType)
   deriving Eq

Foreign/Matlab/Internal.hsc

@@ -1,5 +1,4 @@
 {-# LANGUAGE Trustworthy #-}
-{-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
 module Foreign.Matlab.Internal (
@@ -31,39 +30,19 @@ module Foreign.Matlab.Internal (
     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
+import           Foreign.Matlab.Optics
 import           Foreign.Matlab.Util
 
 #include <matrix.h>
 
 type MIO a = IO a
 
-
--- 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 /=)
 

Foreign/Matlab/Optics.hsc

@@ -0,0 +1,53 @@
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+-- | A few Optics definitions used by this project. These definitions are either
+-- | copied or copmatible with those from the `lens` package.
+module Foreign.Matlab.Optics where
+
+import           Data.Coerce (Coercible, coerce)
+import           Data.Profunctor
+import           Data.Profunctor.Unsafe ((.#))
+
+type Lens s t a b = forall f. Functor f => (a -> f b) -> s -> f t
+
+type Lens' s a = Lens s s a a
+
+
+-- | Build a 'Lens' from a getter and a setter.
+--
+-- @
+-- 'lens' :: 'Functor' f => (s -> a) -> (s -> b -> t) -> (a -> f b) -> s -> f t
+-- @
+--
+-- >>> s ^. lens getter setter
+-- getter s
+--
+-- >>> s & lens getter setter .~ b
+-- setter s b
+--
+-- >>> s & lens getter setter %~ f
+-- setter s (f (getter s))
+--
+-- @
+-- 'lens' :: (s -> a) -> (s -> a -> s) -> 'Lens'' s a
+-- @
+lens :: (s -> a) -> (s -> b -> t) -> Lens s t a b
+lens sa sbt afb s = sbt s <$> afb (sa s)
+{-# INLINE lens #-}
+
+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
+

matlab.cabal

@@ -53,7 +53,9 @@ library
                       Foreign.Matlab.Array.Able,
                       Foreign.Matlab.Engine.Wrappers,
                       Foreign.Matlab.MAT
-  Other-modules:      Foreign.Matlab.Util, Foreign.Matlab.Internal
+  Other-modules:      Foreign.Matlab.Optics
+                      Foreign.Matlab.Util,
+                      Foreign.Matlab.Internal
   default-extensions: ForeignFunctionInterface,
                       MultiParamTypeClasses,
                       FunctionalDependencies,